diff --git a/Cargo.lock b/Cargo.lock
index 300752a8a..028058eae 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -15,7 +15,7 @@ dependencies = [
 
 [[package]]
 name = "aho-corasick"
-version = "0.7.4"
+version = "0.7.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "memchr 2.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -29,22 +29,13 @@ dependencies = [
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "argon2rs"
-version = "0.2.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "blake2-rfc 0.2.18 (registry+https://github.com/rust-lang/crates.io-index)",
- "scoped_threadpool 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "arr_macro"
 version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "arr_macro_impl 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "proc-macro-hack 0.5.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro-hack 0.5.9 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -52,11 +43,16 @@ name = "arr_macro_impl"
 version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro-hack 0.5.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro-hack 0.5.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.44 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "arrayref"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "arrayvec"
 version = "0.4.11"
@@ -78,7 +74,7 @@ name = "atty"
 version = "0.2.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -89,13 +85,13 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "backtrace"
-version = "0.3.33"
+version = "0.3.34"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "backtrace-sys 0.1.31 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
- "rustc-demangle 0.1.15 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rustc-demangle 0.1.16 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -103,8 +99,16 @@ name = "backtrace-sys"
 version = "0.1.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "cc 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "base64"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "byteorder 1.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -114,7 +118,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "autocfg 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 1.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -143,14 +147,15 @@ dependencies = [
  "byte-tools 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "crypto-mac 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "digest 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "opaque-debug 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "opaque-debug 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
-name = "blake2-rfc"
-version = "0.2.18"
+name = "blake2b_simd"
+version = "0.5.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
+ "arrayref 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "arrayvec 0.4.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "constant_time_eq 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -199,13 +204,13 @@ name = "caseless"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "regex 1.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-normalization 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "cc"
-version = "1.0.37"
+version = "1.0.40"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -255,7 +260,7 @@ name = "cpython"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "python3-sys 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -281,6 +286,15 @@ name = "crossbeam-utils"
 version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "crossbeam-utils"
+version = "0.6.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "crypto-mac"
 version = "0.7.0"
@@ -308,8 +322,8 @@ name = "dirs"
 version = "1.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
- "redox_users 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
+ "redox_users 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -319,8 +333,8 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
  "strsim 0.9.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -334,7 +348,7 @@ name = "ena"
 version = "0.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -344,8 +358,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "atty 0.2.13 (registry+https://github.com/rust-lang/crates.io-index)",
  "humantime 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "termcolor 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -354,7 +368,7 @@ name = "failure"
 version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "backtrace 0.3.33 (registry+https://github.com/rust-lang/crates.io-index)",
+ "backtrace 0.3.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure_derive 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -365,7 +379,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.44 (registry+https://github.com/rust-lang/crates.io-index)",
  "synstructure 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -385,8 +399,8 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "lazy_static 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
  "thread-id 3.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -398,7 +412,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "flame 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.44 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -408,19 +422,19 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "flame 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "indexmap 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "flate2"
-version = "1.0.9"
+version = "1.0.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "crc32fast 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
  "libz-sys 1.0.25 (registry+https://github.com/rust-lang/crates.io-index)",
- "miniz_oxide_c_api 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "miniz_oxide 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -451,7 +465,7 @@ name = "gethostname"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -501,10 +515,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "js-sys"
-version = "0.3.25"
+version = "0.3.26"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "wasm-bindgen 0.2.48 (registry+https://github.com/rust-lang/crates.io-index)",
+ "wasm-bindgen 0.2.49 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -535,10 +549,10 @@ dependencies = [
  "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lalrpop-util 0.16.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "petgraph 0.4.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex-syntax 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex-syntax 0.6.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
  "sha2 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "string_cache 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "term 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -562,29 +576,29 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "lexical"
-version = "2.2.1"
+version = "2.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "lexical-core 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lexical-core 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "lexical-core"
-version = "0.4.2"
+version = "0.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "ryu 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ryu 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "stackvector 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "static_assertions 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "static_assertions 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "libc"
-version = "0.2.60"
+version = "0.2.62"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -592,8 +606,8 @@ name = "libz-sys"
 version = "1.0.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "cc 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
  "pkg-config 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)",
  "vcpkg 0.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -603,12 +617,12 @@ name = "log"
 version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "log"
-version = "0.4.7"
+version = "0.4.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -631,7 +645,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "block-buffer 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "digest 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "opaque-debug 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "opaque-debug 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -647,17 +661,6 @@ dependencies = [
  "adler32 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "miniz_oxide_c_api"
-version = "0.2.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-dependencies = [
- "cc 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)",
- "crc32fast 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
- "miniz_oxide 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "new_debug_unreachable"
 version = "1.0.3"
@@ -669,9 +672,9 @@ version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "bitflags 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "cc 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
  "void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -681,9 +684,9 @@ version = "0.14.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "bitflags 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "cc 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
  "void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -708,7 +711,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "num-integer 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -717,7 +720,7 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -748,12 +751,12 @@ name = "num_cpus"
 version = "1.10.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "opaque-debug"
-version = "0.2.2"
+version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -799,12 +802,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "proc-macro-hack"
-version = "0.5.8"
+version = "0.5.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
- "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -815,13 +818,21 @@ dependencies = [
  "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "proc-macro2"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "pwd"
 version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -829,8 +840,8 @@ name = "python3-sys"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -846,6 +857,14 @@ dependencies = [
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "quote"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "proc-macro2 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "rand"
 version = "0.5.6"
@@ -853,7 +872,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "fuchsia-cprng 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -864,9 +883,9 @@ version = "0.6.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "autocfg 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_chacha 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand_core 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_hc 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_isaac 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_jitter 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -890,12 +909,12 @@ name = "rand_core"
 version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "rand_core 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "rand_core"
-version = "0.4.0"
+version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -919,8 +938,8 @@ name = "rand_jitter"
 version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand_core 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -931,8 +950,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "fuchsia-cprng 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand_core 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rdrand 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -943,7 +962,7 @@ version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "autocfg 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand_core 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rand_core 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -969,13 +988,13 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "redox_users"
-version = "0.3.0"
+version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "argon2rs 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_os 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.56 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rust-argon2 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -987,19 +1006,18 @@ dependencies = [
  "memchr 2.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex-syntax 0.5.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "utf8-ranges 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "utf8-ranges 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "regex"
-version = "1.1.9"
+version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "aho-corasick 0.7.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "aho-corasick 0.7.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "memchr 2.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex-syntax 0.6.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex-syntax 0.6.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "utf8-ranges 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1007,20 +1025,27 @@ name = "regex-syntax"
 version = "0.5.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "ucd-util 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ucd-util 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "regex-syntax"
-version = "0.6.8"
+version = "0.6.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "rust-argon2"
+version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "ucd-util 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "base64 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "blake2b_simd 0.5.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-utils 0.6.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "rustc-demangle"
-version = "0.1.15"
+version = "0.1.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -1049,7 +1074,7 @@ dependencies = [
  "env_logger 0.5.13 (registry+https://github.com/rust-lang/crates.io-index)",
  "flame 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "flamescope 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustpython-compiler 0.1.0",
  "rustpython-parser 0.1.0",
  "rustpython-vm 0.1.0",
@@ -1064,7 +1089,7 @@ dependencies = [
  "bitflags 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-bigint 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-complex 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1085,12 +1110,12 @@ version = "0.1.0"
 dependencies = [
  "bincode 1.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "maplit 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "proc-macro-hack 0.5.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro-hack 0.5.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustpython-bytecode 0.1.0",
  "rustpython-compiler 0.1.0",
- "syn 0.15.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.44 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1099,7 +1124,7 @@ version = "0.1.0"
 dependencies = [
  "lalrpop 0.16.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "lalrpop-util 0.16.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-bigint 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1125,15 +1150,16 @@ dependencies = [
  "digest 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "flame 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "flamer 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "flate2 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "flate2 1.0.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "gethostname 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "hex 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "hexf-parse 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "indexmap 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "lexical 2.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lexical 2.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
  "libz-sys 1.0.25 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "maplit 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1145,16 +1171,16 @@ dependencies = [
  "num-rational 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.10.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "proc-macro-hack 0.5.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro-hack 0.5.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "pwd 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.5.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "regex 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_version_runtime 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustpython-bytecode 0.1.0",
  "rustpython-compiler 0.1.0",
  "rustpython-derive 0.1.0",
  "rustpython-parser 0.1.0",
- "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.40 (registry+https://github.com/rust-lang/crates.io-index)",
  "sha-1 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "sha2 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1176,16 +1202,16 @@ version = "0.1.0-pre-alpha.2"
 dependencies = [
  "cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures 0.1.28 (registry+https://github.com/rust-lang/crates.io-index)",
- "js-sys 0.3.25 (registry+https://github.com/rust-lang/crates.io-index)",
+ "js-sys 0.3.26 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustpython-compiler 0.1.0",
  "rustpython-parser 0.1.0",
  "rustpython-vm 0.1.0",
- "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde-wasm-bindgen 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "wasm-bindgen 0.2.48 (registry+https://github.com/rust-lang/crates.io-index)",
- "wasm-bindgen-futures 0.3.25 (registry+https://github.com/rust-lang/crates.io-index)",
- "web-sys 0.3.25 (registry+https://github.com/rust-lang/crates.io-index)",
+ "wasm-bindgen 0.2.49 (registry+https://github.com/rust-lang/crates.io-index)",
+ "wasm-bindgen-futures 0.3.26 (registry+https://github.com/rust-lang/crates.io-index)",
+ "web-sys 0.3.26 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1194,8 +1220,8 @@ version = "4.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "dirs 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
- "log 0.4.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "memchr 2.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "nix 0.13.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-segmentation 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1204,21 +1230,11 @@ dependencies = [
  "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "ryu"
-version = "0.2.8"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "ryu"
 version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
-[[package]]
-name = "scoped_threadpool"
-version = "0.1.9"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "semver"
 version = "0.9.0"
@@ -1234,10 +1250,10 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "serde"
-version = "1.0.97"
+version = "1.0.98"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "serde_derive 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1246,19 +1262,19 @@ version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "fnv 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "js-sys 0.3.25 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
- "wasm-bindgen 0.2.48 (registry+https://github.com/rust-lang/crates.io-index)",
+ "js-sys 0.3.26 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
+ "wasm-bindgen 0.2.49 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.97"
+version = "1.0.98"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "syn 0.15.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.15.44 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1268,7 +1284,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "itoa 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "ryu 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.98 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1279,7 +1295,7 @@ dependencies = [
  "block-buffer 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "digest 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "fake-simd 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "opaque-debug 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "opaque-debug 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1290,7 +1306,7 @@ dependencies = [
  "block-buffer 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "digest 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "fake-simd 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "opaque-debug 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "opaque-debug 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1302,7 +1318,7 @@ dependencies = [
  "byte-tools 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "digest 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "keccak 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "opaque-debug 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "opaque-debug 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1331,7 +1347,7 @@ dependencies = [
 
 [[package]]
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-version = "0.2.5"
+version = "0.3.4"
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 [[package]]
@@ -1351,7 +1367,7 @@ dependencies = [
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- "serde 1.0.97 (registry+https://github.com/rust-lang/crates.io-index)",
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@@ -1389,7 +1405,7 @@ version = "0.1.18"
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- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
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@@ -1400,7 +1416,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
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@@ -1408,6 +1424,16 @@ dependencies = [
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 ]
 
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "proc-macro2 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
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@@ -1415,7 +1441,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
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- "syn 0.15.39 (registry+https://github.com/rust-lang/crates.io-index)",
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@@ -1449,7 +1475,7 @@ name = "thread-id"
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 dependencies = [
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
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@@ -1467,7 +1493,7 @@ name = "time"
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 dependencies = [
- "libc 0.2.60 (registry+https://github.com/rust-lang/crates.io-index)",
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@@ -1479,7 +1505,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
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-version = "0.1.3"
+version = "0.1.5"
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 [[package]]
@@ -1778,6 +1804,11 @@ name = "unicode-xid"
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+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+
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@@ -1798,7 +1829,7 @@ dependencies = [
 
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@@ -1828,87 +1859,90 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
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 "checksum synstructure 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)" = "02353edf96d6e4dc81aea2d8490a7e9db177bf8acb0e951c24940bf866cb313f"
 "checksum term 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "fa63644f74ce96fbeb9b794f66aff2a52d601cbd5e80f4b97123e3899f4570f1"
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@@ -2139,7 +2176,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum thread_local 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c6b53e329000edc2b34dbe8545fd20e55a333362d0a321909685a19bd28c3f1b"
 "checksum time 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)" = "db8dcfca086c1143c9270ac42a2bbd8a7ee477b78ac8e45b19abfb0cbede4b6f"
 "checksum typenum 1.10.0 (registry+https://github.com/rust-lang/crates.io-index)" = "612d636f949607bdf9b123b4a6f6d966dedf3ff669f7f045890d3a4a73948169"
-"checksum ucd-util 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "535c204ee4d8434478593480b8f86ab45ec9aae0e83c568ca81abf0fd0e88f86"
+"checksum ucd-util 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "fa9b3b49edd3468c0e6565d85783f51af95212b6fa3986a5500954f00b460874"
 "checksum unic 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e31748f3e294dc6a9243a44686e8155a162af9a11cd56e07c0ebbc530b2a8a87"
 "checksum unic-bidi 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1356b759fb6a82050666f11dce4b6fe3571781f1449f3ef78074e408d468ec09"
 "checksum unic-char 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "af25df79bd134107f088ba725d9c470600f16263205d0be36c75e75b020bac0a"
@@ -2173,23 +2210,24 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum unicode-segmentation 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1967f4cdfc355b37fd76d2a954fb2ed3871034eb4f26d60537d88795cfc332a9"
 "checksum unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "882386231c45df4700b275c7ff55b6f3698780a650026380e72dabe76fa46526"
 "checksum unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "fc72304796d0818e357ead4e000d19c9c174ab23dc11093ac919054d20a6a7fc"
+"checksum unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "826e7639553986605ec5979c7dd957c7895e93eabed50ab2ffa7f6128a75097c"
 "checksum unicode_categories 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "39ec24b3121d976906ece63c9daad25b85969647682eee313cb5779fdd69e14e"
 "checksum unicode_names2 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "0dc6c5da0c8d7200f9488cc346bd30ba62bcd9f79ef937ea6573132e3d507df9"
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-"checksum utf8-ranges 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "9d50aa7650df78abf942826607c62468ce18d9019673d4a2ebe1865dbb96ffde"
+"checksum utf8-ranges 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "b4ae116fef2b7fea257ed6440d3cfcff7f190865f170cdad00bb6465bf18ecba"
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diff --git a/DEVELOPMENT.md b/DEVELOPMENT.md
index 9fd818536..7ddf53fc6 100644
--- a/DEVELOPMENT.md
+++ b/DEVELOPMENT.md
@@ -1,9 +1,91 @@
 # RustPython Development Guide and Tips
 
+RustPython attracts developers with interest and experience in Rust, Python,
+or WebAssembly. Whether you are familiar with Rust, Python, or 
+WebAssembly, the goal of this Development Guide is to give you the basics to
+get set up for developing RustPython and contributing to this project. 
+
+The contents of the Development Guide include:
+
+- [Setting up a development environment](#setting-up-a-development-environment)
+- [Code style](#code-style)
+- [Testing](#testing)
+- [Profiling](#profiling)
+- [Code organization](#code-organization)
+- [Understanding internals](#understanding-internals)
+- [Questions](#questions)
+
+## Setting up a development environment
+
+RustPython requires the following:
+
+- Rust 1.36 or higher
+    - To check Rust version: `rustc --version` 
+    - If you have `rustup` on your system, enter to update to the latest
+      stable version: `rustup update stable`
+    - If you do not have Rust installed, use [rustup](https://rustup.rs/) to
+      do so.
+- CPython version 3.7.4 or higher
+    - CPython can be installed by your operating system's package manager,
+      from the [Python website](https://www.python.org/downloads/), or
+      using a third-party distribution, such as 
+      [Anaconda](https://www.anaconda.com/distribution/).
+- [Optional] The Python package, `pytest`, is used for testing Python code
+  snippets. To install, enter `python3 -m pip install pytest`.
+
+## Code style
+
+The Rust code style used is the default
+[rustfmt](https://github.com/rust-lang/rustfmt) codestyle. Please format your
+code accordingly. We also use [clippy](https://github.com/rust-lang/rust-clippy)
+to detect rust code issues. 
+
+Python code should follow the 
+[PEP 8](https://www.python.org/dev/peps/pep-0008/) style. We also use
+[flake8](http://flake8.pycqa.org/en/latest/) to check Python code style.
+
+## Testing
+
+To test RustPython's functionality, a collection of Python snippets is located
+in the `tests/snippets` directory and can be run using `pytest`:
+
+```shell
+$ cd tests
+$ pytest -v
+```
+
+Rust unit tests can be run with `cargo`:
+
+```shell
+$ cargo test --all
+```
+
+## Profiling
+
+To profile RustPython, build it in `release` mode with the `flame-it` feature.
+This will generate a file `flamescope.json`, which can be viewed at
+https://speedscope.app.
+
+```shell
+$ cargo run --release --features flame-it script.py
+$ cat flamescope.json
+{<json>}
+```
+
+You can specify another file name other than the default by using the
+`--output-file` option to specify a file name (or `stdout` if you specify `-`).
+The `--output-format` option determines the format of the output file.
+The speedscope json format (default), text, or raw html can be passed. There
+exists a raw html viewer which is currently broken, and we welcome a PR to fix it.
+
 ## Code organization
 
+Understanding a new codebase takes time. Here's a brief view of the
+repository's structure:
+
 - `bytecode/src`: python bytecode representation in rust structures
 - `compiler/src`: python compilation to bytecode
+- `derive/src`: Rust language extensions and macros specific to rustpython
 - `parser/src`: python lexing, parsing and ast
 - `Lib`: Carefully selected / copied files from CPython sourcecode. This is
    the python side of the standard library.
@@ -19,42 +101,67 @@
 - `wasm`: Binary crate and resources for WebAssembly build
 - `tests`: integration test snippets
 
-## Code style
+## Understanding Internals
 
-The code style used is the default
-[rustfmt](https://github.com/rust-lang/rustfmt) codestyle. Please format your
-code accordingly. We also use [clippy](https://github.com/rust-lang/rust-clippy)
-to detect rust code issues.
+The RustPython workspace includes the `rustpython` top-level crate. The `Cargo.toml`
+file in the root of the repo provide configuration of the crate and the
+implementation is found in the `src` directory (specifically, 
+`src/main.rs`).
 
-## Testing
+The top-level `rustpython` binary depends on several lower-level crates including:
 
-To test rustpython, there is a collection of python snippets located in the
-`tests/snippets` directory. To run those tests do the following:
+- `rustpython-parser` (implementation in `parser/src`)
+- `rustpython-compiler` (implementation in `compiler/src`)
+- `rustpython-vm` (implementation in `vm/src`)
 
-```shell
-$ cd tests
-$ pytest -v
-```
+Together, these crates provide the functions of a programming language and
+enable a line of code to go through a series of steps:
 
-There also are some unit tests, you can run those with cargo:
+- parse the line of source code into tokens
+- determine if the tokens are valid syntax
+- create an Abstract Syntax Tree (AST)
+- compile the AST into bytecode
+- execute the bytecode in the virtual machine (VM).
 
-```shell
-$ cargo test --all
-```
+### rustpython-parser
 
-## Profiling
+This crate contains the lexer and parser to convert a line of code to
+an Abstract Syntax Tree (AST):
 
-To profile rustpython, simply build in release mode with the `flame-it` feature.
-This will generate a file `flamescope.json`, which you can then view at
-https://speedscope.app.
+- Lexer: `parser/lexer.rs` converts Python source code into tokens
+- Parser: `parser/parser.rs` takes the tokens generated by the lexer and parses
+  the tokens into an AST (Abstract Syntax Tree) where the nodes of the syntax
+  tree are Rust structs and enums.
+  - The Parser relies on `LALRPOP`, a Rust parser generator framework.
+  - More information on parsers and a tutorial can be found in the 
+    [LALRPOP book](https://lalrpop.github.io/lalrpop/README.html).
+- AST: `parser/ast.rs` implements in Rust the Python types and expressions
+  represented by the AST nodes.
 
-```sh
-$ cargo run --release --features flame-it script.py
-$ cat flamescope.json
-{<json>}
-```
+### rustpython-compiler
 
-You can also pass the `--output-file` option to choose which file to output to
-(or stdout if you specify `-`), and the `--output-format` option to choose if
-you want to output in the speedscope json format (default), text, or a raw html
-viewer (currently broken).
+The `rustpython-compiler` crate's purpose is to transform the AST (Abstract Syntax
+Tree) to bytecode. The implementation of the compiler is found in the
+`compiler/src` directory. The compiler implements Python's peephole optimizer
+implementation, Symbol table, and streams in Rust.
+
+Implementation of bytecode structure in Rust is found in the `bytecode/src`
+directory. The `bytecode/src/bytecode.rs` contains the representation of
+instructions and operations in Rust. Further information about Python's
+bytecode instructions can be found in the
+[Python documentation](https://docs.python.org/3/library/dis.html#bytecodes).
+
+### rustpython-vm
+
+The `rustpython-vm` crate has the important job of running the virtual machine that
+executes Python's instructions. The `vm/src` directory contains code to
+implement the read and evaluation loop that fetches and dispatches
+instructions. This directory also contains the implementation of the
+Python Standard Library modules in Rust (`vm/src/stdlib`). In Python
+everything can be represented as an Object. `vm/src/obj` directory holds
+the Rust code used to represent a Python Object and its methods.
+
+## Questions
+
+Have you tried these steps and have a question, please chat with us on
+[gitter](https://gitter.im/rustpython/Lobby).
diff --git a/Lib/unittest/__main__.py b/Lib/unittest/__main__.py
index 711653832..e5876f569 100644
--- a/Lib/unittest/__main__.py
+++ b/Lib/unittest/__main__.py
@@ -2,8 +2,7 @@
 
 import sys
 if sys.argv[0].endswith("__main__.py"):
-    # FIXME change to `import os.path` as it was for cpython once `import os.path` works
-    import os
+    import os.path
     # We change sys.argv[0] to make help message more useful
     # use executable without path, unquoted
     # (it's just a hint anyway)
diff --git a/bytecode/src/bytecode.rs b/bytecode/src/bytecode.rs
index 2946954da..3802429b8 100644
--- a/bytecode/src/bytecode.rs
+++ b/bytecode/src/bytecode.rs
@@ -84,10 +84,7 @@ pub enum Instruction {
         symbols: Vec<String>,
         level: usize,
     },
-    ImportStar {
-        name: Option<String>,
-        level: usize,
-    },
+    ImportStar,
     ImportFrom {
         name: String,
     },
@@ -429,7 +426,7 @@ impl Instruction {
                 format!("{:?}", symbols),
                 level
             ),
-            ImportStar { name, level } => w!(ImportStar, format!("{:?}", name), level),
+            ImportStar => w!(ImportStar),
             ImportFrom { name } => w!(ImportFrom, name),
             LoadName { name, scope } => w!(LoadName, name, format!("{:?}", scope)),
             StoreName { name, scope } => w!(StoreName, name, format!("{:?}", scope)),
diff --git a/compiler/src/compile.rs b/compiler/src/compile.rs
index baa838fea..23b46f1b9 100644
--- a/compiler/src/compile.rs
+++ b/compiler/src/compile.rs
@@ -188,7 +188,19 @@ impl<O: OutputStream> Compiler<O> {
     ) -> Result<(), CompileError> {
         let size_before = self.output_stack.len();
         self.symbol_table_stack.push(symbol_table);
-        self.compile_statements(&program.statements)?;
+
+        let (statements, doc) = get_doc(&program.statements);
+        if let Some(value) = doc {
+            self.emit(Instruction::LoadConst {
+                value: bytecode::Constant::String { value },
+            });
+            self.emit(Instruction::StoreName {
+                name: "__doc__".to_owned(),
+                scope: bytecode::NameScope::Global,
+            });
+        }
+        self.compile_statements(statements)?;
+
         assert_eq!(self.output_stack.len(), size_before);
 
         // Emit None at end:
@@ -305,11 +317,15 @@ impl<O: OutputStream> Compiler<O> {
                         symbols: vec![],
                         level: 0,
                     });
-
                     if let Some(alias) = &name.alias {
+                        for part in name.symbol.split('.').skip(1) {
+                            self.emit(Instruction::LoadAttr {
+                                name: part.to_owned(),
+                            });
+                        }
                         self.store_name(alias);
                     } else {
-                        self.store_name(&name.symbol);
+                        self.store_name(name.symbol.split('.').next().unwrap());
                     }
                 }
             }
@@ -322,10 +338,12 @@ impl<O: OutputStream> Compiler<O> {
 
                 if import_star {
                     // from .... import *
-                    self.emit(Instruction::ImportStar {
+                    self.emit(Instruction::Import {
                         name: module.clone(),
+                        symbols: vec!["*".to_owned()],
                         level: *level,
                     });
+                    self.emit(Instruction::ImportStar);
                 } else {
                     // from mod import a, b as c
                     // First, determine the fromlist (for import lib):
@@ -1891,30 +1909,36 @@ impl<O: OutputStream> Compiler<O> {
     }
 
     fn compile_string(&mut self, string: &ast::StringGroup) -> Result<(), CompileError> {
-        match string {
-            ast::StringGroup::Joined { values } => {
-                for value in values {
-                    self.compile_string(value)?;
+        if let Some(value) = try_get_constant_string(string) {
+            self.emit(Instruction::LoadConst {
+                value: bytecode::Constant::String { value },
+            });
+        } else {
+            match string {
+                ast::StringGroup::Joined { values } => {
+                    for value in values {
+                        self.compile_string(value)?;
+                    }
+                    self.emit(Instruction::BuildString { size: values.len() })
+                }
+                ast::StringGroup::Constant { value } => {
+                    self.emit(Instruction::LoadConst {
+                        value: bytecode::Constant::String {
+                            value: value.to_string(),
+                        },
+                    });
+                }
+                ast::StringGroup::FormattedValue {
+                    value,
+                    conversion,
+                    spec,
+                } => {
+                    self.compile_expression(value)?;
+                    self.emit(Instruction::FormatValue {
+                        conversion: conversion.map(compile_conversion_flag),
+                        spec: spec.clone(),
+                    });
                 }
-                self.emit(Instruction::BuildString { size: values.len() })
-            }
-            ast::StringGroup::Constant { value } => {
-                self.emit(Instruction::LoadConst {
-                    value: bytecode::Constant::String {
-                        value: value.to_string(),
-                    },
-                });
-            }
-            ast::StringGroup::FormattedValue {
-                value,
-                conversion,
-                spec,
-            } => {
-                self.compile_expression(value)?;
-                self.emit(Instruction::FormatValue {
-                    conversion: conversion.map(compile_conversion_flag),
-                    spec: spec.clone(),
-                });
             }
         }
         Ok(())
@@ -1994,13 +2018,11 @@ impl<O: OutputStream> Compiler<O> {
 }
 
 fn get_doc(body: &[ast::Statement]) -> (&[ast::Statement], Option<String>) {
-    if let Some(val) = body.get(0) {
+    if let Some((val, body_rest)) = body.split_first() {
         if let ast::StatementType::Expression { ref expression } = val.node {
             if let ast::ExpressionType::String { value } = &expression.node {
-                if let ast::StringGroup::Constant { ref value } = value {
-                    if let Some((_, body_rest)) = body.split_first() {
-                        return (body_rest, Some(value.to_string()));
-                    }
+                if let Some(value) = try_get_constant_string(value) {
+                    return (body_rest, Some(value.to_string()));
                 }
             }
         }
@@ -2008,6 +2030,27 @@ fn get_doc(body: &[ast::Statement]) -> (&[ast::Statement], Option<String>) {
     (body, None)
 }
 
+fn try_get_constant_string(string: &ast::StringGroup) -> Option<String> {
+    fn get_constant_string_inner(out_string: &mut String, string: &ast::StringGroup) -> bool {
+        match string {
+            ast::StringGroup::Constant { value } => {
+                out_string.push_str(&value);
+                true
+            }
+            ast::StringGroup::Joined { values } => values
+                .iter()
+                .all(|value| get_constant_string_inner(out_string, value)),
+            ast::StringGroup::FormattedValue { .. } => false,
+        }
+    }
+    let mut out_string = String::new();
+    if get_constant_string_inner(&mut out_string, string) {
+        Some(out_string)
+    } else {
+        None
+    }
+}
+
 fn compile_location(location: &ast::Location) -> bytecode::Location {
     bytecode::Location::new(location.row(), location.column())
 }
diff --git a/compiler/src/symboltable.rs b/compiler/src/symboltable.rs
index d91f32dc7..8e44bc755 100644
--- a/compiler/src/symboltable.rs
+++ b/compiler/src/symboltable.rs
@@ -388,7 +388,10 @@ impl SymbolTableBuilder {
                         self.register_name(alias, SymbolUsage::Assigned)?;
                     } else {
                         // `import module`
-                        self.register_name(&name.symbol, SymbolUsage::Assigned)?;
+                        self.register_name(
+                            name.symbol.split('.').next().unwrap(),
+                            SymbolUsage::Assigned,
+                        )?;
                     }
                 }
             }
diff --git a/src/main.rs b/src/main.rs
index 42d0462b6..5e2d7c60c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -312,7 +312,7 @@ fn run_rustpython(vm: &VirtualMachine, matches: &ArgMatches) -> PyResult<()> {
     }
 
     let scope = vm.new_scope_with_builtins();
-    let main_module = vm.ctx.new_module("__main__", scope.globals.clone());
+    let main_module = vm.new_module("__main__", scope.globals.clone());
 
     vm.get_attribute(vm.sys_module.clone(), "modules")?
         .set_item("__main__", main_module, vm)?;
@@ -359,7 +359,7 @@ fn run_module(vm: &VirtualMachine, module: &str) -> PyResult<()> {
     debug!("Running module {}", module);
     let runpy = vm.import("runpy", &vm.ctx.new_tuple(vec![]), 0)?;
     let run_module_as_main = vm.get_attribute(runpy, "_run_module_as_main")?;
-    vm.invoke(run_module_as_main, vec![vm.new_str(module.to_owned())])?;
+    vm.invoke(&run_module_as_main, vec![vm.new_str(module.to_owned())])?;
     Ok(())
 }
 
diff --git a/tests/snippets/builtin_complex.py b/tests/snippets/builtin_complex.py
index 64b4570c1..f751a95a5 100644
--- a/tests/snippets/builtin_complex.py
+++ b/tests/snippets/builtin_complex.py
@@ -145,3 +145,7 @@ assert '(1+1j)' == str(1+1j)
 assert '(1-1j)' == str(1-1j)
 assert '(1+1j)' == repr(1+1j)
 assert '(1-1j)' == repr(1-1j)
+
+# __getnewargs__
+assert (3 + 5j).__getnewargs__() == (3.0, 5.0)
+assert (5j).__getnewargs__() == (0.0, 5.0)
\ No newline at end of file
diff --git a/tests/snippets/builtin_round.py b/tests/snippets/builtin_round.py
new file mode 100644
index 000000000..6d116b307
--- /dev/null
+++ b/tests/snippets/builtin_round.py
@@ -0,0 +1,21 @@
+from testutils import assertRaises
+
+assert round(0) == 0
+assert isinstance(round(0), int)
+assert round(0.0) == 0
+assert isinstance(round(0.0), int)
+
+assert round(0, None) == 0
+assert isinstance(round(0, None), int)
+assert round(0.0, None) == 0
+assert isinstance(round(0, None), int)
+
+assert round(0, 0) == 0
+assert isinstance(round(0, 0), int)
+assert round(0.0, 0) == 0.0  # Cannot check the type
+assert isinstance(round(0.0, 0), float)
+
+with assertRaises(TypeError):
+    round(0, 0.0)
+with assertRaises(TypeError):
+    round(0.0, 0.0)
diff --git a/tests/snippets/ellipsis.py b/tests/snippets/ellipsis.py
index 20bb3a33c..5316b9f86 100644
--- a/tests/snippets/ellipsis.py
+++ b/tests/snippets/ellipsis.py
@@ -11,6 +11,23 @@ assert b is c
 assert b is d
 assert d is e
 
+assert Ellipsis.__repr__() == 'Ellipsis'
+assert Ellipsis.__reduce__() == 'Ellipsis'
+assert type(Ellipsis).__new__(type(Ellipsis)) == Ellipsis
+assert type(Ellipsis).__reduce__(Ellipsis) == 'Ellipsis'
+try:
+    type(Ellipsis).__new__(type(1))
+except TypeError:
+    pass
+else:
+    assert False, '`Ellipsis.__new__` should only accept `type(Ellipsis)` as argument'
+try:
+    type(Ellipsis).__reduce__(1)
+except TypeError:
+    pass
+else:
+    assert False, '`Ellipsis.__reduce__` should only accept `Ellipsis` as argument'
+
 assert Ellipsis is ...
 Ellipsis = 2
 assert Ellipsis is not ...
diff --git a/tests/snippets/floats.py b/tests/snippets/floats.py
index 0200e5a36..6139295f4 100644
--- a/tests/snippets/floats.py
+++ b/tests/snippets/floats.py
@@ -151,12 +151,20 @@ assert float(1.2) == 1.2
 assert math.trunc(1.2) == 1
 assert_raises(OverflowError, float('inf').__trunc__)
 assert_raises(ValueError, float('nan').__trunc__)
-assert 0.5.__round__() == 0.0
-assert 1.5.__round__() == 2.0
+assert isinstance(0.5.__round__(), int)
+assert isinstance(1.5.__round__(), int)
+assert 0.5.__round__() == 0
+assert 1.5.__round__() == 2
+assert isinstance(0.5.__round__(0), float)
+assert isinstance(1.5.__round__(0), float)
 assert 0.5.__round__(0) == 0.0
 assert 1.5.__round__(0) == 2.0
-assert 0.5.__round__(None) == 0.0
-assert 1.5.__round__(None) == 2.0
+assert isinstance(0.5.__round__(None), int)
+assert isinstance(1.5.__round__(None), int)
+assert 0.5.__round__(None) == 0
+assert 1.5.__round__(None) == 2
+assert_raises(TypeError, lambda: 0.5.__round__(0.0))
+assert_raises(TypeError, lambda: 1.5.__round__(0.0))
 assert_raises(OverflowError, float('inf').__round__)
 assert_raises(ValueError, float('nan').__round__)
 
diff --git a/tests/snippets/ints.py b/tests/snippets/ints.py
index d05848361..0e89d44f3 100644
--- a/tests/snippets/ints.py
+++ b/tests/snippets/ints.py
@@ -167,3 +167,16 @@ class F(float):
         return 3
 
 assert int(F(1.2)) == 3
+
+assert isinstance((0).__round__(), int)
+assert isinstance((1).__round__(), int)
+assert (0).__round__() == 0
+assert (1).__round__() == 1
+assert isinstance((0).__round__(0), int)
+assert isinstance((1).__round__(0), int)
+assert (0).__round__(0) == 0
+assert (1).__round__(0) == 1
+assert_raises(TypeError, lambda: (0).__round__(None))
+assert_raises(TypeError, lambda: (1).__round__(None))
+assert_raises(TypeError, lambda: (0).__round__(0.0))
+assert_raises(TypeError, lambda: (1).__round__(0.0))
\ No newline at end of file
diff --git a/tests/snippets/json_snippet.py b/tests/snippets/json_snippet.py
index 15866ab86..d47266b58 100644
--- a/tests/snippets/json_snippet.py
+++ b/tests/snippets/json_snippet.py
@@ -1,5 +1,6 @@
 from testutils import assert_raises
 import json
+from io import StringIO
 
 def round_trip_test(obj):
     # serde_json and Python's json module produce slightly differently spaced
@@ -7,63 +8,129 @@ def round_trip_test(obj):
     # proxy
     return obj == json.loads(json.dumps(obj))
 
+def json_dump(obj):
+    f = StringIO()
+    json.dump(obj, f)
+    f.seek(0)
+    return f.getvalue()
+
+def json_load(obj):
+    f = StringIO(obj)
+    return json.load(f)
+
 assert '"string"' == json.dumps("string")
+assert '"string"' == json_dump("string")
+
 assert "1" == json.dumps(1)
+assert "1" == json_dump(1)
+
 assert "1.0" == json.dumps(1.0)
+assert "1.0" == json_dump(1.0)
+
 assert "true" == json.dumps(True)
+assert "true" == json_dump(True)
+
 assert "false" == json.dumps(False)
+assert "false" == json_dump(False)
+
 assert 'null' == json.dumps(None)
+assert 'null' == json_dump(None)
 
 assert '[]' == json.dumps([])
+assert '[]' == json_dump([])
+
 assert '[1]' == json.dumps([1])
+assert '[1]' == json_dump([1])
+
 assert '[[1]]' == json.dumps([[1]])
+assert '[[1]]' == json_dump([[1]])
+
 assert round_trip_test([1, "string", 1.0, True])
 
 assert '[]' == json.dumps(())
+assert '[]' == json_dump(())
+
 assert '[1]' == json.dumps((1,))
+assert '[1]' == json_dump((1,))
+
 assert '[[1]]' == json.dumps(((1,),))
+assert '[[1]]' == json_dump(((1,),))
 # tuples don't round-trip through json
 assert [1, "string", 1.0, True] == json.loads(json.dumps((1, "string", 1.0, True)))
 
 assert '{}' == json.dumps({})
+assert '{}' == json_dump({})
 assert round_trip_test({'a': 'b'})
 
 # should reject non-str keys in jsons
 assert_raises(json.JSONDecodeError, lambda: json.loads('{3: "abc"}'))
+assert_raises(json.JSONDecodeError, lambda: json_load('{3: "abc"}'))
 
 # should serialize non-str keys as strings
 assert json.dumps({'3': 'abc'}) == json.dumps({3: 'abc'})
 
 assert 1 == json.loads("1")
+assert 1 == json_load("1")
+
 assert -1 == json.loads("-1")
+assert -1 == json_load("-1")
+
 assert 1.0 == json.loads("1.0")
+assert 1.0 == json_load("1.0")
+
 assert -1.0 == json.loads("-1.0")
+assert -1.0 == json_load("-1.0")
+
 assert "str" == json.loads('"str"')
+assert "str" == json_load('"str"')
+
 assert True is json.loads('true')
+assert True is json_load('true')
+
 assert False is json.loads('false')
+assert False is json_load('false')
+
 assert None is json.loads('null')
+assert None is json_load('null')
+
 assert [] == json.loads('[]')
+assert [] == json_load('[]')
+
 assert ['a'] == json.loads('["a"]')
+assert ['a'] == json_load('["a"]')
+
 assert [['a'], 'b'] == json.loads('[["a"], "b"]')
+assert [['a'], 'b'] == json_load('[["a"], "b"]')
 
 class String(str): pass
 
 assert "string" == json.loads(String('"string"'))
+assert "string" == json_load(String('"string"'))
+
 assert '"string"' == json.dumps(String("string"))
+assert '"string"' == json_dump(String("string"))
 
 class Int(int): pass
 class Float(float): pass
 
 assert '1' == json.dumps(Int(1))
+assert '1' == json_dump(Int(1))
+
 assert '0.5' == json.dumps(Float(0.5))
+assert '0.5' == json_dump(Float(0.5))
 
 class List(list): pass
 class Tuple(tuple): pass
 class Dict(dict): pass
 
 assert '[1]' == json.dumps(List([1]))
+assert '[1]' == json_dump(List([1]))
+
 assert json.dumps((1, "string", 1.0, True)) == json.dumps(Tuple((1, "string", 1.0, True)))
+assert json_dump((1, "string", 1.0, True)) == json_dump(Tuple((1, "string", 1.0, True)))
+
 assert json.dumps({'a': 'b'}) == json.dumps(Dict({'a': 'b'}))
+assert json_dump({'a': 'b'}) == json_dump(Dict({'a': 'b'}))
 
 # big ints should not crash VM
 # TODO: test for correct output when actual serialization implemented and doesn’t throw
diff --git a/tests/snippets/object.py b/tests/snippets/object.py
index 6845a0b3e..663a2cd76 100644
--- a/tests/snippets/object.py
+++ b/tests/snippets/object.py
@@ -7,6 +7,10 @@ myobj = MyObject()
 assert myobj == myobj
 assert not myobj != myobj
 
+object.__subclasshook__() == NotImplemented
+object.__subclasshook__(1) == NotImplemented
+object.__subclasshook__(1, 2) == NotImplemented
+
 assert MyObject().__eq__(MyObject()) == NotImplemented
 assert MyObject().__ne__(MyObject()) == NotImplemented
 assert MyObject().__lt__(MyObject()) == NotImplemented
diff --git a/tests/snippets/stdlib_functools.py b/tests/snippets/stdlib_functools.py
new file mode 100644
index 000000000..bd95f0e81
--- /dev/null
+++ b/tests/snippets/stdlib_functools.py
@@ -0,0 +1,79 @@
+from functools import reduce
+from testutils import assertRaises
+
+class Squares:
+    def __init__(self, max):
+        self.max = max
+        self.sofar = []
+
+    def __len__(self):
+        return len(self.sofar)
+
+    def __getitem__(self, i):
+        if not 0 <= i < self.max: raise IndexError
+        n = len(self.sofar)
+        while n <= i:
+            self.sofar.append(n*n)
+            n += 1
+        return self.sofar[i]
+
+def add(a, b):
+    return a + b
+
+assert reduce(add, ['a', 'b', 'c']) == 'abc'
+assert reduce(add, ['a', 'b', 'c'], str(42)) == '42abc'
+assert reduce(add, [['a', 'c'], [], ['d', 'w']], []) == ['a','c','d','w']
+assert reduce(add, [['a', 'c'], [], ['d', 'w']], []) == ['a','c','d','w']
+assert reduce(lambda x, y: x*y, range(2, 21), 1) == 2432902008176640000
+assert reduce(add, Squares(10)) == 285
+assert reduce(add, Squares(10), 0) == 285
+assert reduce(add, Squares(0), 0) == 0
+assert reduce(42, "1") == "1"
+assert reduce(42, "", "1") == "1"
+
+with assertRaises(TypeError):
+    reduce()
+
+with assertRaises(TypeError):
+    reduce(42, 42)
+
+with assertRaises(TypeError):
+    reduce(42, 42, 42)
+
+class TestFailingIter:
+    def __iter__(self):
+        raise RuntimeError
+
+with assertRaises(RuntimeError):
+    reduce(add, TestFailingIter())
+
+assert reduce(add, [], None) == None
+assert reduce(add, [], 42) == 42
+
+class BadSeq:
+    def __getitem__(self, index):
+        raise ValueError
+with assertRaises(ValueError):
+    reduce(42, BadSeq())
+
+# Test reduce()'s use of iterators.
+class SequenceClass:
+    def __init__(self, n):
+        self.n = n
+    def __getitem__(self, i):
+        if 0 <= i < self.n:
+            return i
+        else:
+            raise IndexError
+
+assert reduce(add, SequenceClass(5)) == 10
+assert reduce(add, SequenceClass(5), 42) == 52
+with assertRaises(TypeError):
+    reduce(add, SequenceClass(0))
+
+assert reduce(add, SequenceClass(0), 42) == 42
+assert reduce(add, SequenceClass(1)) == 0
+assert reduce(add, SequenceClass(1), 42) == 42
+
+d = {"one": 1, "two": 2, "three": 3}
+assert reduce(add, d) == "".join(d.keys())
diff --git a/tests/snippets/stdlib_io.py b/tests/snippets/stdlib_io.py
index 184146081..78f1287a9 100644
--- a/tests/snippets/stdlib_io.py
+++ b/tests/snippets/stdlib_io.py
@@ -1,5 +1,6 @@
 from io import BufferedReader, FileIO, StringIO, BytesIO
 import os
+from testutils import assertRaises
 
 fi = FileIO('README.md')
 assert fi.seekable()
@@ -23,3 +24,9 @@ fd = os.open('README.md', os.O_RDONLY)
 with FileIO(fd) as fio:
 	res2 = fio.read()
 	assert res == res2
+
+fi = FileIO('README.md')
+fi.read()
+fi.close()
+with assertRaises(ValueError):
+    fi.read()
diff --git a/tests/snippets/stdlib_socket.py b/tests/snippets/stdlib_socket.py
index 581100c58..f34c83e47 100644
--- a/tests/snippets/stdlib_socket.py
+++ b/tests/snippets/stdlib_socket.py
@@ -119,6 +119,12 @@ with assertRaises(OSError):
 with assertRaises(OSError):
 	socket.inet_aton("test")
 
+with assertRaises(OverflowError):
+	socket.htonl(-1)
+
+assert socket.htonl(0)==0
+assert socket.htonl(10)==167772160
+
 assert socket.inet_aton("127.0.0.1")==b"\x7f\x00\x00\x01"
 assert socket.inet_aton("255.255.255.255")==b"\xff\xff\xff\xff"
 
diff --git a/vm/Cargo.toml b/vm/Cargo.toml
index 64160547a..b1f1873f2 100644
--- a/vm/Cargo.toml
+++ b/vm/Cargo.toml
@@ -79,3 +79,6 @@ libz-sys = "1.0.25"
 gethostname = "0.2.0"
 subprocess = "0.1.18"
 num_cpus = "1.0"
+
+[target."cfg(windows)".dependencies]
+kernel32-sys = "0.2.2"
diff --git a/vm/Lib/_bootstrap_external.py b/vm/Lib/_bootstrap_external.py
index 124948ef4..c1ceac96c 100644
--- a/vm/Lib/_bootstrap_external.py
+++ b/vm/Lib/_bootstrap_external.py
@@ -26,6 +26,16 @@ _CASE_INSENSITIVE_PLATFORMS =  (_CASE_INSENSITIVE_PLATFORMS_BYTES_KEY
                                 + _CASE_INSENSITIVE_PLATFORMS_STR_KEY)
 
 
+def _w_long(x):
+    """Convert a 32-bit integer to little-endian."""
+    return (int(x) & 0xFFFFFFFF).to_bytes(4, 'little')
+
+
+def _r_long(int_bytes):
+    """Convert 4 bytes in little-endian to an integer."""
+    return int.from_bytes(int_bytes, 'little')
+
+
 def _make_relax_case():
     if sys.platform.startswith(_CASE_INSENSITIVE_PLATFORMS):
         if sys.platform.startswith(_CASE_INSENSITIVE_PLATFORMS_STR_KEY):
diff --git a/vm/src/builtins.rs b/vm/src/builtins.rs
index b3b901e8a..33ad00044 100644
--- a/vm/src/builtins.rs
+++ b/vm/src/builtins.rs
@@ -37,7 +37,7 @@ fn builtin_abs(x: PyObjectRef, vm: &VirtualMachine) -> PyResult {
     let method = vm.get_method_or_type_error(x.clone(), "__abs__", || {
         format!("bad operand type for abs(): '{}'", x.class().name)
     })?;
-    vm.invoke(method, PyFuncArgs::new(vec![], vec![]))
+    vm.invoke(&method, PyFuncArgs::new(vec![], vec![]))
 }
 
 fn builtin_all(iterable: PyIterable<bool>, vm: &VirtualMachine) -> PyResult<bool> {
@@ -395,7 +395,7 @@ fn builtin_len(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
     let method = vm.get_method_or_type_error(obj.clone(), "__len__", || {
         format!("object of type '{}' has no len()", obj.class().name)
     })?;
-    vm.invoke(method, PyFuncArgs::default())
+    vm.invoke(&method, PyFuncArgs::default())
 }
 
 fn builtin_locals(vm: &VirtualMachine) -> PyDictRef {
@@ -428,15 +428,15 @@ fn builtin_max(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
     let mut x = candidates_iter.next().unwrap();
     // TODO: this key function looks pretty duplicate. Maybe we can create
     // a local function?
-    let mut x_key = if let Some(f) = &key_func {
-        vm.invoke(f.clone(), vec![x.clone()])?
+    let mut x_key = if let Some(ref f) = &key_func {
+        vm.invoke(f, vec![x.clone()])?
     } else {
         x.clone()
     };
 
     for y in candidates_iter {
-        let y_key = if let Some(f) = &key_func {
-            vm.invoke(f.clone(), vec![y.clone()])?
+        let y_key = if let Some(ref f) = &key_func {
+            vm.invoke(f, vec![y.clone()])?
         } else {
             y.clone()
         };
@@ -476,15 +476,15 @@ fn builtin_min(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
     let mut x = candidates_iter.next().unwrap();
     // TODO: this key function looks pretty duplicate. Maybe we can create
     // a local function?
-    let mut x_key = if let Some(f) = &key_func {
-        vm.invoke(f.clone(), vec![x.clone()])?
+    let mut x_key = if let Some(ref f) = &key_func {
+        vm.invoke(f, vec![x.clone()])?
     } else {
         x.clone()
     };
 
     for y in candidates_iter {
-        let y_key = if let Some(f) = &key_func {
-            vm.invoke(f.clone(), vec![y.clone()])?
+        let y_key = if let Some(ref f) = &key_func {
+            vm.invoke(f, vec![y.clone()])?
         } else {
             y.clone()
         };
@@ -711,7 +711,7 @@ fn builtin_reversed(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(vm, args, required = [(obj, None)]);
 
     if let Some(reversed_method) = vm.get_method(obj.clone(), "__reversed__") {
-        vm.invoke(reversed_method?, PyFuncArgs::default())
+        vm.invoke(&reversed_method?, PyFuncArgs::default())
     } else {
         vm.get_method_or_type_error(obj.clone(), "__getitem__", || {
             "argument to reversed() must be a sequence".to_string()
@@ -734,9 +734,19 @@ fn builtin_round(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
         optional = [(ndigits, None)]
     );
     if let Some(ndigits) = ndigits {
-        let ndigits = vm.call_method(ndigits, "__int__", vec![])?;
-        let rounded = vm.call_method(number, "__round__", vec![ndigits])?;
-        Ok(rounded)
+        if objtype::isinstance(ndigits, &vm.ctx.int_type()) {
+            let ndigits = vm.call_method(ndigits, "__int__", vec![])?;
+            let rounded = vm.call_method(number, "__round__", vec![ndigits])?;
+            Ok(rounded)
+        } else if vm.ctx.none().is(ndigits) {
+            let rounded = &vm.call_method(number, "__round__", vec![])?;
+            Ok(vm.ctx.new_int(objint::get_value(rounded).clone()))
+        } else {
+            Err(vm.new_type_error(format!(
+                "'{}' object cannot be interpreted as an integer",
+                ndigits.class().name
+            )))
+        }
     } else {
         // without a parameter, the result type is coerced to int
         let rounded = &vm.call_method(number, "__round__", vec![])?;
@@ -777,7 +787,7 @@ fn builtin_sum(iterable: PyIterable, start: OptionalArg, vm: &VirtualMachine) ->
 
 // Should be renamed to builtin___import__?
 fn builtin_import(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
-    vm.invoke(vm.import_func.borrow().clone(), args)
+    vm.invoke(&vm.import_func.borrow(), args)
 }
 
 fn builtin_vars(obj: OptionalArg, vm: &VirtualMachine) -> PyResult {
@@ -964,13 +974,13 @@ pub fn builtin_build_class_(
 
     // Prepare uses full __getattribute__ resolution chain.
     let prepare = vm.get_attribute(metaclass.clone().into_object(), "__prepare__")?;
-    let namespace = vm.invoke(prepare, vec![name_obj.clone(), bases.clone()])?;
+    let namespace = vm.invoke(&prepare, vec![name_obj.clone(), bases.clone()])?;
 
     let namespace: PyDictRef = TryFromObject::try_from_object(vm, namespace)?;
 
     let cells = vm.ctx.new_dict();
 
-    vm.invoke_with_locals(function, cells.clone(), namespace.clone())?;
+    vm.invoke_with_locals(&function, cells.clone(), namespace.clone())?;
 
     namespace.set_item("__name__", name_obj.clone(), vm)?;
     namespace.set_item("__qualname__", qualified_name.into_object(), vm)?;
diff --git a/vm/src/exceptions.rs b/vm/src/exceptions.rs
index 48fa0ce7a..a78a286b8 100644
--- a/vm/src/exceptions.rs
+++ b/vm/src/exceptions.rs
@@ -3,7 +3,8 @@ use crate::obj::objsequence;
 use crate::obj::objtuple::{PyTuple, PyTupleRef};
 use crate::obj::objtype;
 use crate::obj::objtype::PyClassRef;
-use crate::pyobject::{create_type, IdProtocol, PyContext, PyObjectRef, PyResult, TypeProtocol};
+use crate::pyobject::{IdProtocol, PyContext, PyObjectRef, PyResult, TypeProtocol};
+use crate::types::create_type;
 use crate::vm::VirtualMachine;
 use itertools::Itertools;
 use std::fs::File;
diff --git a/vm/src/frame.rs b/vm/src/frame.rs
index f338b6413..0f56596ee 100644
--- a/vm/src/frame.rs
+++ b/vm/src/frame.rs
@@ -198,10 +198,7 @@ impl Frame {
                 ref symbols,
                 ref level,
             } => self.import(vm, name, symbols, *level),
-            bytecode::Instruction::ImportStar {
-                ref name,
-                ref level,
-            } => self.import_star(vm, name, *level),
+            bytecode::Instruction::ImportStar => self.import_star(vm),
             bytecode::Instruction::ImportFrom { ref name } => self.import_from(vm, name),
             bytecode::Instruction::LoadName {
                 ref name,
@@ -488,7 +485,7 @@ impl Frame {
 
                 // Call function:
                 let func_ref = self.pop_value();
-                let value = vm.invoke(func_ref, args)?;
+                let value = vm.invoke(&func_ref, args)?;
                 self.push_value(value);
                 Ok(None)
             }
@@ -599,7 +596,7 @@ impl Frame {
                 if !expr.is(&vm.get_none()) {
                     let repr = vm.to_repr(&expr)?;
                     // TODO: implement sys.displayhook
-                    if let Ok(print) = vm.get_attribute(vm.builtins.clone(), "print") {
+                    if let Ok(ref print) = vm.get_attribute(vm.builtins.clone(), "print") {
                         vm.invoke(print, vec![repr.into_object()])?;
                     }
                 }
@@ -740,25 +737,23 @@ impl Frame {
         // Load attribute, and transform any error into import error.
         let obj = vm
             .get_attribute(module, name)
-            .map_err(|_| vm.new_import_error(format!("cannot import name '{}'", name)));
-        self.push_value(obj?);
+            .map_err(|_| vm.new_import_error(format!("cannot import name '{}'", name)))?;
+        self.push_value(obj);
         Ok(None)
     }
 
     #[cfg_attr(feature = "flame-it", flame("Frame"))]
-    fn import_star(
-        &self,
-        vm: &VirtualMachine,
-        module: &Option<String>,
-        level: usize,
-    ) -> FrameResult {
-        let module = module.clone().unwrap_or_default();
-        let module = vm.import(&module, &vm.ctx.new_tuple(vec![]), level)?;
+    fn import_star(&self, vm: &VirtualMachine) -> FrameResult {
+        let module = self.pop_value();
 
         // Grab all the names from the module and put them in the context
         if let Some(dict) = &module.dict {
             for (k, v) in dict {
-                self.scope.store_name(&vm, &objstr::get_value(&k), v);
+                let k = vm.to_str(&k)?;
+                let k = k.as_str();
+                if !k.starts_with('_') {
+                    self.scope.store_name(&vm, k, v);
+                }
             }
         }
         Ok(None)
diff --git a/vm/src/function.rs b/vm/src/function.rs
index d199860b1..9874309fc 100644
--- a/vm/src/function.rs
+++ b/vm/src/function.rs
@@ -393,6 +393,18 @@ impl<T> OptionalArg<T> {
     }
 }
 
+pub type OptionalOption<T> = OptionalArg<Option<T>>;
+
+impl<T> OptionalOption<T> {
+    #[inline]
+    pub fn flat_option(self) -> Option<T> {
+        match self {
+            Present(Some(value)) => Some(value),
+            _ => None,
+        }
+    }
+}
+
 impl<T> FromArgs for OptionalArg<T>
 where
     T: TryFromObject,
diff --git a/vm/src/import.rs b/vm/src/import.rs
index 2caaeda53..267adfc86 100644
--- a/vm/src/import.rs
+++ b/vm/src/import.rs
@@ -17,14 +17,14 @@ pub fn init_importlib(vm: &VirtualMachine, external: bool) -> PyResult {
     let importlib = import_frozen(vm, "_frozen_importlib")?;
     let impmod = import_builtin(vm, "_imp")?;
     let install = vm.get_attribute(importlib.clone(), "_install")?;
-    vm.invoke(install, vec![vm.sys_module.clone(), impmod])?;
+    vm.invoke(&install, vec![vm.sys_module.clone(), impmod])?;
     vm.import_func
         .replace(vm.get_attribute(importlib.clone(), "__import__")?);
     if external && cfg!(feature = "rustpython-compiler") {
         flame_guard!("install_external");
         let install_external =
             vm.get_attribute(importlib.clone(), "_install_external_importers")?;
-        vm.invoke(install_external, vec![])?;
+        vm.invoke(&install_external, vec![])?;
         // Set pyc magic number to commit hash. Should be changed when bytecode will be more stable.
         let importlib_external =
             vm.import("_frozen_importlib_external", &vm.ctx.new_tuple(vec![]), 0)?;
@@ -87,7 +87,7 @@ pub fn import_codeobj(
     if set_file_attr {
         attrs.set_item("__file__", vm.new_str(code_obj.source_path.to_owned()), vm)?;
     }
-    let module = vm.ctx.new_module(module_name, attrs.clone());
+    let module = vm.new_module(module_name, attrs.clone());
 
     // Store module in cache to prevent infinite loop with mutual importing libs:
     let sys_modules = vm.get_attribute(vm.sys_module.clone(), "modules")?;
diff --git a/vm/src/lib.rs b/vm/src/lib.rs
index 766ece06f..0f66f7f8b 100644
--- a/vm/src/lib.rs
+++ b/vm/src/lib.rs
@@ -68,6 +68,7 @@ pub mod scope;
 pub mod stdlib;
 mod sysmodule;
 mod traceback;
+pub mod types;
 pub mod util;
 mod version;
 mod vm;
diff --git a/vm/src/macros.rs b/vm/src/macros.rs
index 5ae975d8e..ea10abfdc 100644
--- a/vm/src/macros.rs
+++ b/vm/src/macros.rs
@@ -117,7 +117,7 @@ macro_rules! no_kwargs {
 #[macro_export]
 macro_rules! py_module {
     ( $vm:expr, $module_name:expr, { $($name:expr => $value:expr),* $(,)* }) => {{
-        let module = $vm.ctx.new_module($module_name, $vm.ctx.new_dict());
+        let module = $vm.new_module($module_name, $vm.ctx.new_dict());
         $vm.set_attr(&module, "__name__", $vm.ctx.new_str($module_name.to_string())).unwrap();
         $(
             $vm.set_attr(&module, $name, $value).unwrap();
diff --git a/vm/src/obj/objbool.rs b/vm/src/obj/objbool.rs
index 6988028ea..19d95889f 100644
--- a/vm/src/obj/objbool.rs
+++ b/vm/src/obj/objbool.rs
@@ -28,7 +28,7 @@ pub fn boolval(vm: &VirtualMachine, obj: PyObjectRef) -> PyResult<bool> {
         Some(method_or_err) => {
             // If descriptor returns Error, propagate it further
             let method = method_or_err?;
-            let bool_obj = vm.invoke(method, PyFuncArgs::default())?;
+            let bool_obj = vm.invoke(&method, PyFuncArgs::default())?;
             match bool_obj.payload::<PyInt>() {
                 Some(int_obj) => !int_obj.as_bigint().is_zero(),
                 None => {
@@ -42,7 +42,7 @@ pub fn boolval(vm: &VirtualMachine, obj: PyObjectRef) -> PyResult<bool> {
         None => match vm.get_method(obj.clone(), "__len__") {
             Some(method_or_err) => {
                 let method = method_or_err?;
-                let bool_obj = vm.invoke(method, PyFuncArgs::default())?;
+                let bool_obj = vm.invoke(&method, PyFuncArgs::default())?;
                 match bool_obj.payload::<PyInt>() {
                     Some(int_obj) => !int_obj.as_bigint().is_zero(),
                     None => {
@@ -66,7 +66,7 @@ Returns True when the argument x is true, False otherwise.
 The builtins True and False are the only two instances of the class bool.
 The class bool is a subclass of the class int, and cannot be subclassed.";
 
-    let bool_type = &context.bool_type;
+    let bool_type = &context.types.bool_type;
     extend_class!(context, bool_type, {
         "__new__" => context.new_rustfunc(bool_new),
         "__repr__" => context.new_rustfunc(bool_repr),
diff --git a/vm/src/obj/objbytearray.rs b/vm/src/obj/objbytearray.rs
index 51d608b09..c3d722ea7 100644
--- a/vm/src/obj/objbytearray.rs
+++ b/vm/src/obj/objbytearray.rs
@@ -78,14 +78,14 @@ impl PyValue for PyByteArray {
 
 /// Fill bytearray class methods dictionary.
 pub fn init(context: &PyContext) {
-    PyByteArrayRef::extend_class(context, &context.bytearray_type);
-    let bytearray_type = &context.bytearray_type;
+    PyByteArrayRef::extend_class(context, &context.types.bytearray_type);
+    let bytearray_type = &context.types.bytearray_type;
     extend_class!(context, bytearray_type, {
     "fromhex" => context.new_rustfunc(PyByteArrayRef::fromhex),
     "maketrans" => context.new_rustfunc(PyByteInner::maketrans),
     });
 
-    PyByteArrayIterator::extend_class(context, &context.bytearrayiterator_type);
+    PyByteArrayIterator::extend_class(context, &context.types.bytearrayiterator_type);
 }
 
 #[pyimpl]
diff --git a/vm/src/obj/objbytes.rs b/vm/src/obj/objbytes.rs
index c67a044b2..c39b3203d 100644
--- a/vm/src/obj/objbytes.rs
+++ b/vm/src/obj/objbytes.rs
@@ -85,14 +85,14 @@ pub fn get_value<'a>(obj: &'a PyObjectRef) -> impl Deref<Target = Vec<u8>> + 'a
 }
 
 pub fn init(context: &PyContext) {
-    PyBytesRef::extend_class(context, &context.bytes_type);
-    let bytes_type = &context.bytes_type;
+    PyBytesRef::extend_class(context, &context.types.bytes_type);
+    let bytes_type = &context.types.bytes_type;
     extend_class!(context, bytes_type, {
     "fromhex" => context.new_rustfunc(PyBytesRef::fromhex),
     "maketrans" => context.new_rustfunc(PyByteInner::maketrans),
 
     });
-    PyBytesIterator::extend_class(context, &context.bytesiterator_type);
+    PyBytesIterator::extend_class(context, &context.types.bytesiterator_type);
 }
 
 #[pyimpl]
diff --git a/vm/src/obj/objclassmethod.rs b/vm/src/obj/objclassmethod.rs
index 10b3106ec..38ef47d9e 100644
--- a/vm/src/obj/objclassmethod.rs
+++ b/vm/src/obj/objclassmethod.rs
@@ -65,5 +65,5 @@ impl PyClassMethod {
 }
 
 pub fn init(context: &PyContext) {
-    PyClassMethod::extend_class(context, &context.classmethod_type);
+    PyClassMethod::extend_class(context, &context.types.classmethod_type);
 }
diff --git a/vm/src/obj/objcode.rs b/vm/src/obj/objcode.rs
index 51a73d614..a1671d0ef 100644
--- a/vm/src/obj/objcode.rs
+++ b/vm/src/obj/objcode.rs
@@ -81,7 +81,7 @@ impl PyCodeRef {
 }
 
 pub fn init(context: &PyContext) {
-    extend_class!(context, &context.code_type, {
+    extend_class!(context, &context.types.code_type, {
         "__new__" => context.new_rustfunc(PyCodeRef::new),
         "__repr__" => context.new_rustfunc(PyCodeRef::repr),
 
diff --git a/vm/src/obj/objcomplex.rs b/vm/src/obj/objcomplex.rs
index b32fd8f74..c20431d00 100644
--- a/vm/src/obj/objcomplex.rs
+++ b/vm/src/obj/objcomplex.rs
@@ -41,7 +41,7 @@ impl From<Complex64> for PyComplex {
 }
 
 pub fn init(context: &PyContext) {
-    PyComplex::extend_class(context, &context.complex_type);
+    PyComplex::extend_class(context, &context.types.complex_type);
 }
 
 pub fn get_value(obj: &PyObjectRef) -> Complex64 {
@@ -258,4 +258,12 @@ impl PyComplex {
         let ret = Wrapping(re_hash) + Wrapping(im_hash) * Wrapping(pyhash::IMAG);
         ret.0
     }
+
+    #[pymethod(name = "__getnewargs__")]
+    fn complex_getnewargs(&self, vm: &VirtualMachine) -> PyResult {
+        let Complex64 { re, im } = self.value;
+        Ok(vm
+            .ctx
+            .new_tuple(vec![vm.ctx.new_float(re), vm.ctx.new_float(im)]))
+    }
 }
diff --git a/vm/src/obj/objdict.rs b/vm/src/obj/objdict.rs
index e68c6b6a4..09fc08a96 100644
--- a/vm/src/obj/objdict.rs
+++ b/vm/src/obj/objdict.rs
@@ -210,7 +210,7 @@ impl PyDictRef {
         }
         if let Some(method_or_err) = vm.get_method(self.clone().into_object(), "__missing__") {
             let method = method_or_err?;
-            return vm.invoke(method, vec![key]);
+            return vm.invoke(&method, vec![key]);
         }
         Err(vm.new_key_error(key.clone()))
     }
@@ -423,7 +423,7 @@ macro_rules! dict_iterator {
 
         impl PyValue for $name {
             fn class(vm: &VirtualMachine) -> PyClassRef {
-                vm.ctx.$class.clone()
+                vm.ctx.types.$class.clone()
             }
         }
 
@@ -473,7 +473,7 @@ macro_rules! dict_iterator {
 
         impl PyValue for $iter_name {
             fn class(vm: &VirtualMachine) -> PyClassRef {
-                vm.ctx.$iter_class.clone()
+                vm.ctx.types.$iter_class.clone()
             }
         }
     };
@@ -511,7 +511,7 @@ dict_iterator! {
 }
 
 pub fn init(context: &PyContext) {
-    extend_class!(context, &context.dict_type, {
+    extend_class!(context, &context.types.dict_type, {
         "__bool__" => context.new_rustfunc(PyDictRef::bool),
         "__len__" => context.new_rustfunc(PyDictRef::len),
         "__contains__" => context.new_rustfunc(PyDictRef::contains),
@@ -536,10 +536,10 @@ pub fn init(context: &PyContext) {
         "popitem" => context.new_rustfunc(PyDictRef::popitem),
     });
 
-    PyDictKeys::extend_class(context, &context.dictkeys_type);
-    PyDictKeyIterator::extend_class(context, &context.dictkeyiterator_type);
-    PyDictValues::extend_class(context, &context.dictvalues_type);
-    PyDictValueIterator::extend_class(context, &context.dictvalueiterator_type);
-    PyDictItems::extend_class(context, &context.dictitems_type);
-    PyDictItemIterator::extend_class(context, &context.dictitemiterator_type);
+    PyDictKeys::extend_class(context, &context.types.dictkeys_type);
+    PyDictKeyIterator::extend_class(context, &context.types.dictkeyiterator_type);
+    PyDictValues::extend_class(context, &context.types.dictvalues_type);
+    PyDictValueIterator::extend_class(context, &context.types.dictvalueiterator_type);
+    PyDictItems::extend_class(context, &context.types.dictitems_type);
+    PyDictItemIterator::extend_class(context, &context.types.dictitemiterator_type);
 }
diff --git a/vm/src/obj/objellipsis.rs b/vm/src/obj/objellipsis.rs
index cb188e1f1..3b2b6d8bf 100644
--- a/vm/src/obj/objellipsis.rs
+++ b/vm/src/obj/objellipsis.rs
@@ -1,20 +1,30 @@
-use crate::function::PyFuncArgs;
-use crate::pyobject::{PyContext, PyResult};
+use crate::obj::objtype::{issubclass, PyClassRef};
+use crate::pyobject::{PyContext, PyEllipsisRef, PyResult};
 use crate::vm::VirtualMachine;
 
 pub fn init(context: &PyContext) {
     extend_class!(context, &context.ellipsis_type, {
         "__new__" => context.new_rustfunc(ellipsis_new),
-        "__repr__" => context.new_rustfunc(ellipsis_repr)
+        "__repr__" => context.new_rustfunc(ellipsis_repr),
+        "__reduce__" => context.new_rustfunc(ellipsis_reduce),
     });
 }
 
-fn ellipsis_new(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
-    arg_check!(vm, args, required = [(_cls, None)]);
-    Ok(vm.ctx.ellipsis())
+fn ellipsis_new(cls: PyClassRef, vm: &VirtualMachine) -> PyResult {
+    if issubclass(&cls, &vm.ctx.ellipsis_type) {
+        Ok(vm.ctx.ellipsis())
+    } else {
+        Err(vm.new_type_error(format!(
+            "ellipsis.__new__({ty}): {ty} is not a subtype of ellipsis",
+            ty = cls,
+        )))
+    }
 }
 
-fn ellipsis_repr(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
-    arg_check!(vm, args, required = [(_cls, None)]);
-    Ok(vm.new_str("Ellipsis".to_string()))
+fn ellipsis_repr(_self: PyEllipsisRef, _vm: &VirtualMachine) -> String {
+    "Ellipsis".to_string()
+}
+
+fn ellipsis_reduce(_self: PyEllipsisRef, _vm: &VirtualMachine) -> String {
+    "Ellipsis".to_string()
 }
diff --git a/vm/src/obj/objenumerate.rs b/vm/src/obj/objenumerate.rs
index 56d232272..0ce34c689 100644
--- a/vm/src/obj/objenumerate.rs
+++ b/vm/src/obj/objenumerate.rs
@@ -68,8 +68,8 @@ impl PyEnumerate {
 }
 
 pub fn init(context: &PyContext) {
-    PyEnumerate::extend_class(context, &context.enumerate_type);
-    extend_class!(context, &context.enumerate_type, {
+    PyEnumerate::extend_class(context, &context.types.enumerate_type);
+    extend_class!(context, &context.types.enumerate_type, {
         "__new__" => context.new_rustfunc(enumerate_new),
     });
 }
diff --git a/vm/src/obj/objfilter.rs b/vm/src/obj/objfilter.rs
index 24800d6aa..8fa3fef3c 100644
--- a/vm/src/obj/objfilter.rs
+++ b/vm/src/obj/objfilter.rs
@@ -52,7 +52,7 @@ impl PyFilter {
             } else {
                 // the predicate itself can raise StopIteration which does stop the filter
                 // iteration
-                vm.invoke(predicate.clone(), vec![next_obj.clone()])?
+                vm.invoke(&predicate, vec![next_obj.clone()])?
             };
             if objbool::boolval(vm, predicate_value)? {
                 return Ok(next_obj);
@@ -67,8 +67,8 @@ impl PyFilter {
 }
 
 pub fn init(context: &PyContext) {
-    PyFilter::extend_class(context, &context.filter_type);
-    extend_class!(context, &context.filter_type, {
+    PyFilter::extend_class(context, &context.types.filter_type);
+    extend_class!(context, &context.types.filter_type, {
         "__new__" => context.new_rustfunc(filter_new),
     });
 }
diff --git a/vm/src/obj/objfloat.rs b/vm/src/obj/objfloat.rs
index cfac52aa9..b0dbaebe2 100644
--- a/vm/src/obj/objfloat.rs
+++ b/vm/src/obj/objfloat.rs
@@ -440,25 +440,38 @@ impl PyFloat {
             OptionalArg::Missing => None,
             OptionalArg::Present(ref value) => {
                 if !vm.get_none().is(value) {
-                    let ndigits = if objtype::isinstance(value, &vm.ctx.int_type()) {
-                        objint::get_value(value)
-                    } else {
+                    if !objtype::isinstance(value, &vm.ctx.int_type()) {
                         return Err(vm.new_type_error(format!(
-                            "TypeError: '{}' object cannot be interpreted as an integer",
+                            "'{}' object cannot be interpreted as an integer",
                             value.class().name
                         )));
                     };
-                    if ndigits.is_zero() {
-                        None
-                    } else {
-                        Some(ndigits)
-                    }
+                    // Only accept int type ndigits
+                    let ndigits = objint::get_value(value);
+                    Some(ndigits)
                 } else {
                     None
                 }
             }
         };
-        if ndigits.is_none() {
+
+        if let Some(ndigits) = ndigits {
+            if ndigits.is_zero() {
+                let fract = self.value.fract();
+                let value = if (fract.abs() - 0.5).abs() < std::f64::EPSILON {
+                    if self.value.trunc() % 2.0 == 0.0 {
+                        self.value - fract
+                    } else {
+                        self.value + fract
+                    }
+                } else {
+                    self.value.round()
+                };
+                Ok(vm.ctx.new_float(value))
+            } else {
+                Ok(vm.ctx.not_implemented())
+            }
+        } else {
             let fract = self.value.fract();
             let value = if (fract.abs() - 0.5).abs() < std::f64::EPSILON {
                 if self.value.trunc() % 2.0 == 0.0 {
@@ -471,8 +484,6 @@ impl PyFloat {
             };
             let int = try_to_bigint(value, vm)?;
             Ok(vm.ctx.new_int(int))
-        } else {
-            Ok(vm.ctx.not_implemented())
         }
     }
 
@@ -612,12 +623,12 @@ pub fn make_float(vm: &VirtualMachine, obj: &PyObjectRef) -> PyResult<f64> {
                 obj.class().name
             )
         })?;
-        let result = vm.invoke(method, vec![])?;
+        let result = vm.invoke(&method, vec![])?;
         Ok(get_value(&result))
     }
 }
 
 #[rustfmt::skip] // to avoid line splitting
 pub fn init(context: &PyContext) {
-    PyFloat::extend_class(context, &context.float_type);
+    PyFloat::extend_class(context, &context.types.float_type);
 }
diff --git a/vm/src/obj/objframe.rs b/vm/src/obj/objframe.rs
index 73f4e9b91..efc833270 100644
--- a/vm/src/obj/objframe.rs
+++ b/vm/src/obj/objframe.rs
@@ -9,7 +9,7 @@ use crate::pyobject::{PyContext, PyObjectRef, PyResult};
 use crate::vm::VirtualMachine;
 
 pub fn init(context: &PyContext) {
-    extend_class!(context, &context.frame_type, {
+    extend_class!(context, &context.types.frame_type, {
         "__new__" => context.new_rustfunc(FrameRef::new),
         "__repr__" => context.new_rustfunc(FrameRef::repr),
         "f_locals" => context.new_property(FrameRef::flocals),
diff --git a/vm/src/obj/objfunction.rs b/vm/src/obj/objfunction.rs
index 1c7ff642a..d33ec97fe 100644
--- a/vm/src/obj/objfunction.rs
+++ b/vm/src/obj/objfunction.rs
@@ -42,7 +42,7 @@ impl PyValue for PyFunction {
 
 impl PyFunctionRef {
     fn call(self, args: Args, kwargs: KwArgs, vm: &VirtualMachine) -> PyResult {
-        vm.invoke(self.into_object(), (&args, &kwargs))
+        vm.invoke(&self.into_object(), (&args, &kwargs))
     }
 
     fn code(self, _vm: &VirtualMachine) -> PyCodeRef {
@@ -78,7 +78,7 @@ impl PyValue for PyMethod {
 }
 
 pub fn init(context: &PyContext) {
-    let function_type = &context.function_type;
+    let function_type = &context.types.function_type;
     extend_class!(context, function_type, {
         "__get__" => context.new_rustfunc(bind_method),
         "__call__" => context.new_rustfunc(PyFunctionRef::call),
@@ -87,7 +87,7 @@ pub fn init(context: &PyContext) {
         "__kwdefaults__" => context.new_property(PyFunctionRef::kwdefaults),
     });
 
-    let builtin_function_or_method_type = &context.builtin_function_or_method_type;
+    let builtin_function_or_method_type = &context.types.builtin_function_or_method_type;
     extend_class!(context, builtin_function_or_method_type, {
         "__get__" => context.new_rustfunc(bind_method)
     });
diff --git a/vm/src/obj/objgenerator.rs b/vm/src/obj/objgenerator.rs
index 2c51778fd..a26be543d 100644
--- a/vm/src/obj/objgenerator.rs
+++ b/vm/src/obj/objgenerator.rs
@@ -75,5 +75,5 @@ fn handle_execution_result(result: ExecutionResult, vm: &VirtualMachine) -> PyRe
 }
 
 pub fn init(ctx: &PyContext) {
-    PyGenerator::extend_class(ctx, &ctx.generator_type);
+    PyGenerator::extend_class(ctx, &ctx.types.generator_type);
 }
diff --git a/vm/src/obj/objint.rs b/vm/src/obj/objint.rs
index e7533752a..41fb1a9bd 100644
--- a/vm/src/obj/objint.rs
+++ b/vm/src/obj/objint.rs
@@ -9,13 +9,14 @@ use crate::function::{KwArgs, OptionalArg, PyFuncArgs};
 use crate::obj::objtype::PyClassRef;
 use crate::pyhash;
 use crate::pyobject::{
-    IntoPyObject, PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue, TryFromObject,
-    TypeProtocol,
+    IdProtocol, IntoPyObject, PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue,
+    TryFromObject, TypeProtocol,
 };
 use crate::vm::VirtualMachine;
 
 use super::objbyteinner::PyByteInner;
 use super::objbytes::PyBytes;
+use super::objint;
 use super::objstr::{PyString, PyStringRef};
 use super::objtype;
 
@@ -468,8 +469,29 @@ impl PyInt {
         zelf: PyRef<Self>,
         _precision: OptionalArg<PyObjectRef>,
         _vm: &VirtualMachine,
-    ) -> PyIntRef {
-        zelf
+    ) -> PyResult<PyIntRef> {
+        let _ndigits = match _precision {
+            OptionalArg::Missing => None,
+            OptionalArg::Present(ref value) => {
+                if !_vm.get_none().is(value) {
+                    if !objtype::isinstance(value, &_vm.ctx.int_type()) {
+                        return Err(_vm.new_type_error(format!(
+                            "'{}' object cannot be interpreted as an integer",
+                            value.class().name
+                        )));
+                    };
+                    // Only accept int type _ndigits
+                    let _ndigits = objint::get_value(value);
+                    Some(_ndigits)
+                } else {
+                    return Err(_vm.new_type_error(format!(
+                        "'{}' object cannot be interpreted as an integer",
+                        value.class().name
+                    )));
+                }
+            }
+        };
+        Ok(zelf)
     }
 
     #[pymethod(name = "__int__")]
@@ -681,7 +703,7 @@ impl IntOptions {
     fn get_int_value(self, vm: &VirtualMachine) -> PyResult<BigInt> {
         if let OptionalArg::Present(val) = self.val_options {
             let base = if let OptionalArg::Present(base) = self.base {
-                if !objtype::isinstance(&val, &vm.ctx.str_type) {
+                if !objtype::isinstance(&val, &vm.ctx.str_type()) {
                     return Err(vm.new_type_error(
                         "int() can't convert non-string with explicit base".to_string(),
                     ));
@@ -724,7 +746,7 @@ pub fn to_int(vm: &VirtualMachine, obj: &PyObjectRef, mut base: u32) -> PyResult
             let method = vm.get_method_or_type_error(obj.clone(), "__int__", || {
                 format!("int() argument must be a string or a number, not '{}'", obj.class().name)
             })?;
-            let result = vm.invoke(method, PyFuncArgs::default())?;
+            let result = vm.invoke(&method, PyFuncArgs::default())?;
             match result.payload::<PyInt>() {
                 Some(int_obj) => Ok(int_obj.as_bigint().clone()),
                 None => Err(vm.new_type_error(format!(
@@ -776,8 +798,8 @@ fn div_ints(vm: &VirtualMachine, i1: &BigInt, i2: &BigInt) -> PyResult {
 }
 
 pub fn init(context: &PyContext) {
-    PyInt::extend_class(context, &context.int_type);
-    extend_class!(context, &context.int_type, {
+    PyInt::extend_class(context, &context.types.int_type);
+    extend_class!(context, &context.types.int_type, {
         "__new__" => context.new_rustfunc(int_new),
     });
 }
diff --git a/vm/src/obj/objiter.rs b/vm/src/obj/objiter.rs
index 0fcd078c7..53460acfa 100644
--- a/vm/src/obj/objiter.rs
+++ b/vm/src/obj/objiter.rs
@@ -20,7 +20,7 @@ use super::objtype::PyClassRef;
 pub fn get_iter(vm: &VirtualMachine, iter_target: &PyObjectRef) -> PyResult {
     if let Some(method_or_err) = vm.get_method(iter_target.clone(), "__iter__") {
         let method = method_or_err?;
-        vm.invoke(method, vec![])
+        vm.invoke(&method, vec![])
     } else {
         vm.get_method_or_type_error(iter_target.clone(), "__getitem__", || {
             format!("Cannot iterate over {}", iter_target.class().name)
@@ -122,5 +122,5 @@ impl PySequenceIterator {
 }
 
 pub fn init(context: &PyContext) {
-    PySequenceIterator::extend_class(context, &context.iter_type);
+    PySequenceIterator::extend_class(context, &context.types.iter_type);
 }
diff --git a/vm/src/obj/objlist.rs b/vm/src/obj/objlist.rs
index e9b4b40d5..419cdb45d 100644
--- a/vm/src/obj/objlist.rs
+++ b/vm/src/obj/objlist.rs
@@ -755,7 +755,7 @@ fn do_sort(
     for x in values.iter() {
         keys.push(match &key_func {
             None => x.clone(),
-            Some(ref func) => vm.invoke((*func).clone(), vec![x.clone()])?,
+            Some(ref func) => vm.invoke(func, vec![x.clone()])?,
         });
     }
 
@@ -859,7 +859,7 @@ impl PyListReverseIterator {
 
 #[rustfmt::skip] // to avoid line splitting
 pub fn init(context: &PyContext) {
-    let list_type = &context.list_type;
+    let list_type = &context.types.list_type;
 
     let list_doc = "Built-in mutable sequence.\n\n\
                     If no argument is given, the constructor creates a new empty list.\n\
@@ -901,6 +901,6 @@ pub fn init(context: &PyContext) {
         "remove" => context.new_rustfunc(PyListRef::remove)
     });
 
-    PyListIterator::extend_class(context, &context.listiterator_type);
-    PyListReverseIterator::extend_class(context, &context.listreverseiterator_type);
+    PyListIterator::extend_class(context, &context.types.listiterator_type);
+    PyListReverseIterator::extend_class(context, &context.types.listreverseiterator_type);
 }
diff --git a/vm/src/obj/objmap.rs b/vm/src/obj/objmap.rs
index 61fe67c0d..a27b56e8b 100644
--- a/vm/src/obj/objmap.rs
+++ b/vm/src/obj/objmap.rs
@@ -51,7 +51,7 @@ impl PyMap {
             .collect::<Result<Vec<_>, _>>()?;
 
         // the mapper itself can raise StopIteration which does stop the map iteration
-        vm.invoke(self.mapper.clone(), next_objs)
+        vm.invoke(&self.mapper, next_objs)
     }
 
     #[pymethod(name = "__iter__")]
@@ -61,8 +61,8 @@ impl PyMap {
 }
 
 pub fn init(context: &PyContext) {
-    PyMap::extend_class(context, &context.map_type);
-    extend_class!(context, &context.map_type, {
+    PyMap::extend_class(context, &context.types.map_type);
+    extend_class!(context, &context.types.map_type, {
         "__new__" => context.new_rustfunc(map_new),
     });
 }
diff --git a/vm/src/obj/objmappingproxy.rs b/vm/src/obj/objmappingproxy.rs
index 243a8c89c..b38e9d1ef 100644
--- a/vm/src/obj/objmappingproxy.rs
+++ b/vm/src/obj/objmappingproxy.rs
@@ -13,7 +13,7 @@ pub type PyMappingProxyRef = PyRef<PyMappingProxy>;
 
 impl PyValue for PyMappingProxy {
     fn class(vm: &VirtualMachine) -> PyClassRef {
-        vm.ctx.mappingproxy_type.clone()
+        vm.ctx.types.mappingproxy_type.clone()
     }
 }
 
@@ -38,5 +38,5 @@ impl PyMappingProxy {
 }
 
 pub fn init(context: &PyContext) {
-    PyMappingProxy::extend_class(context, &context.mappingproxy_type)
+    PyMappingProxy::extend_class(context, &context.types.mappingproxy_type)
 }
diff --git a/vm/src/obj/objmemory.rs b/vm/src/obj/objmemory.rs
index 7e1628d13..ed4687032 100644
--- a/vm/src/obj/objmemory.rs
+++ b/vm/src/obj/objmemory.rs
@@ -47,5 +47,5 @@ impl PyValue for PyMemoryView {
 }
 
 pub fn init(ctx: &PyContext) {
-    PyMemoryView::extend_class(ctx, &ctx.memoryview_type)
+    PyMemoryView::extend_class(ctx, &ctx.types.memoryview_type)
 }
diff --git a/vm/src/obj/objmodule.rs b/vm/src/obj/objmodule.rs
index 99dff3b26..902418498 100644
--- a/vm/src/obj/objmodule.rs
+++ b/vm/src/obj/objmodule.rs
@@ -1,6 +1,8 @@
+use crate::function::OptionalOption;
+use crate::obj::objdict::PyDictRef;
 use crate::obj::objstr::PyStringRef;
 use crate::obj::objtype::PyClassRef;
-use crate::pyobject::{PyContext, PyRef, PyResult, PyValue};
+use crate::pyobject::{ItemProtocol, PyContext, PyObjectRef, PyRef, PyResult, PyValue};
 use crate::vm::VirtualMachine;
 
 #[derive(Debug)]
@@ -17,15 +19,71 @@ impl PyValue for PyModule {
     }
 }
 
+pub fn init_module_dict(
+    vm: &VirtualMachine,
+    module_dict: &PyDictRef,
+    name: PyObjectRef,
+    doc: PyObjectRef,
+) {
+    module_dict
+        .set_item("__name__", name, vm)
+        .expect("Failed to set __name__ on module");
+    module_dict
+        .set_item("__doc__", doc, vm)
+        .expect("Failed to set __doc__ on module");
+    module_dict
+        .set_item("__package__", vm.get_none(), vm)
+        .expect("Failed to set __package__ on module");
+    module_dict
+        .set_item("__loader__", vm.get_none(), vm)
+        .expect("Failed to set __loader__ on module");
+    module_dict
+        .set_item("__spec__", vm.get_none(), vm)
+        .expect("Failed to set __spec__ on module");
+}
+
 impl PyModuleRef {
-    fn init(self, name: PyStringRef, vm: &VirtualMachine) -> PyResult {
-        vm.set_attr(&self.into_object(), "__name__", name)?;
-        Ok(vm.get_none())
+    fn new(
+        cls: PyClassRef,
+        name: PyStringRef,
+        doc: OptionalOption<PyStringRef>,
+        vm: &VirtualMachine,
+    ) -> PyResult<PyModuleRef> {
+        let zelf = PyModule {
+            name: name.as_str().to_owned(),
+        }
+        .into_ref_with_type(vm, cls)?;
+        init_module_dict(
+            vm,
+            zelf.as_object().dict.as_ref().unwrap(),
+            name.into_object(),
+            doc.flat_option()
+                .map_or_else(|| vm.get_none(), PyRef::into_object),
+        );
+        Ok(zelf)
+    }
+
+    fn getattribute(self, name: PyStringRef, vm: &VirtualMachine) -> PyResult {
+        vm.generic_getattribute(self.as_object().clone(), name.clone())?
+            .ok_or_else(|| {
+                vm.new_attribute_error(format!(
+                    "module '{}' has no attribute '{}'",
+                    self.name, name,
+                ))
+            })
+    }
+
+    fn repr(self, vm: &VirtualMachine) -> PyResult {
+        let importlib = vm.import("_frozen_importlib", &vm.ctx.new_tuple(vec![]), 0)?;
+        let module_repr = vm.get_attribute(importlib, "_module_repr")?;
+        vm.invoke(&module_repr, vec![self.into_object()])
     }
 }
 
 pub fn init(context: &PyContext) {
-    extend_class!(&context, &context.module_type, {
-        "__init__" => context.new_rustfunc(PyModuleRef::init),
+    extend_class!(&context, &context.types.module_type, {
+        "__new__" => context.new_rustfunc(PyModuleRef::new),
+        "__getattribute__" => context.new_rustfunc(PyModuleRef::getattribute),
+        "__repr__" => context.new_rustfunc(PyModuleRef::repr),
     });
 }
diff --git a/vm/src/obj/objnamespace.rs b/vm/src/obj/objnamespace.rs
index f8bfc9369..7ef304c1e 100644
--- a/vm/src/obj/objnamespace.rs
+++ b/vm/src/obj/objnamespace.rs
@@ -28,5 +28,5 @@ impl PyNamespace {
 }
 
 pub fn init(context: &PyContext) {
-    PyNamespace::extend_class(context, &context.namespace_type);
+    PyNamespace::extend_class(context, &context.types.namespace_type);
 }
diff --git a/vm/src/obj/objnone.rs b/vm/src/obj/objnone.rs
index fa23ca1b0..cf1b4d3a5 100644
--- a/vm/src/obj/objnone.rs
+++ b/vm/src/obj/objnone.rs
@@ -64,7 +64,7 @@ impl PyNoneRef {
             if let Ok(property) = PyPropertyRef::try_from_object(vm, descriptor.clone()) {
                 property.instance_binding_get(obj, vm)
             } else {
-                vm.invoke(get_func, vec![descriptor, obj, cls])
+                vm.invoke(&get_func, vec![descriptor, obj, cls])
             }
         }
 
@@ -95,7 +95,7 @@ impl PyNoneRef {
                 Ok(attr)
             }
         } else if let Some(getter) = class_get_attr(&cls, "__getattr__") {
-            vm.invoke(getter, vec![self.into_object(), name.into_object()])
+            vm.invoke(&getter, vec![self.into_object(), name.into_object()])
         } else {
             Err(vm.new_attribute_error(format!("{} has no attribute '{}'", self.as_object(), name)))
         }
diff --git a/vm/src/obj/objobject.rs b/vm/src/obj/objobject.rs
index 8f2408dba..87b1da34a 100644
--- a/vm/src/obj/objobject.rs
+++ b/vm/src/obj/objobject.rs
@@ -24,7 +24,7 @@ impl PyValue for PyInstance {
 pub fn new_instance(vm: &VirtualMachine, mut args: PyFuncArgs) -> PyResult {
     // more or less __new__ operator
     let cls = PyClassRef::try_from_object(vm, args.shift())?;
-    let dict = if cls.is(&vm.ctx.object) {
+    let dict = if cls.is(&vm.ctx.object()) {
         None
     } else {
         Some(vm.ctx.new_dict())
@@ -72,7 +72,7 @@ fn object_setattr(
     if let Some(attr) = objtype::class_get_attr(&cls, &attr_name.value) {
         if let Some(descriptor) = objtype::class_get_attr(&attr.class(), "__set__") {
             return vm
-                .invoke(descriptor, vec![attr, obj.clone(), value])
+                .invoke(&descriptor, vec![attr, obj.clone(), value])
                 .map(|_| ());
         }
     }
@@ -94,7 +94,7 @@ fn object_delattr(obj: PyObjectRef, attr_name: PyStringRef, vm: &VirtualMachine)
 
     if let Some(attr) = objtype::class_get_attr(&cls, &attr_name.value) {
         if let Some(descriptor) = objtype::class_get_attr(&attr.class(), "__delete__") {
-            return vm.invoke(descriptor, vec![attr, obj.clone()]).map(|_| ());
+            return vm.invoke(&descriptor, vec![attr, obj.clone()]).map(|_| ());
         }
     }
 
@@ -118,6 +118,10 @@ fn object_repr(zelf: PyObjectRef, _vm: &VirtualMachine) -> String {
     format!("<{} object at 0x{:x}>", zelf.class().name, zelf.get_id())
 }
 
+fn object_subclasshook(vm: &VirtualMachine, _args: PyFuncArgs) -> PyResult {
+    Ok(vm.ctx.not_implemented())
+}
+
 pub fn object_dir(obj: PyObjectRef, vm: &VirtualMachine) -> PyResult<PyList> {
     let attributes: PyAttributes = objtype::get_attributes(obj.class());
 
@@ -126,7 +130,7 @@ pub fn object_dir(obj: PyObjectRef, vm: &VirtualMachine) -> PyResult<PyList> {
     // Get instance attributes:
     if let Some(object_dict) = &obj.dict {
         vm.invoke(
-            vm.get_attribute(dict.clone().into_object(), "update")?,
+            &vm.get_attribute(dict.clone().into_object(), "update")?,
             object_dict.clone().into_object(),
         )?;
     }
@@ -149,7 +153,7 @@ fn object_format(
 }
 
 pub fn init(context: &PyContext) {
-    let object = &context.object;
+    let object = &context.types.object_type;
     let object_doc = "The most base type";
 
     extend_class!(context, object, {
@@ -179,7 +183,8 @@ pub fn init(context: &PyContext) {
         "__repr__" => context.new_rustfunc(object_repr),
         "__format__" => context.new_rustfunc(object_format),
         "__getattribute__" => context.new_rustfunc(object_getattribute),
-        "__doc__" => context.new_str(object_doc.to_string())
+        "__subclasshook__" => context.new_classmethod(object_subclasshook),
+        "__doc__" => context.new_str(object_doc.to_string()),
     });
 }
 
@@ -218,39 +223,8 @@ fn object_dict_setter(
     ))
 }
 
-fn object_getattribute(obj: PyObjectRef, name_str: PyStringRef, vm: &VirtualMachine) -> PyResult {
-    let name = &name_str.value;
+fn object_getattribute(obj: PyObjectRef, name: PyStringRef, vm: &VirtualMachine) -> PyResult {
     vm_trace!("object.__getattribute__({:?}, {:?})", obj, name);
-    let cls = obj.class();
-
-    if let Some(attr) = objtype::class_get_attr(&cls, &name) {
-        let attr_class = attr.class();
-        if objtype::class_has_attr(&attr_class, "__set__") {
-            if let Some(descriptor) = objtype::class_get_attr(&attr_class, "__get__") {
-                return vm.invoke(descriptor, vec![attr, obj, cls.into_object()]);
-            }
-        }
-    }
-
-    if let Some(obj_attr) = object_getattr(&obj, &name, &vm)? {
-        Ok(obj_attr)
-    } else if let Some(attr) = objtype::class_get_attr(&cls, &name) {
-        vm.call_get_descriptor(attr, obj)
-    } else if let Some(getter) = objtype::class_get_attr(&cls, "__getattr__") {
-        vm.invoke(getter, vec![obj, name_str.into_object()])
-    } else {
-        Err(vm.new_attribute_error(format!("{} has no attribute '{}'", obj, name)))
-    }
-}
-
-fn object_getattr(
-    obj: &PyObjectRef,
-    attr_name: &str,
-    vm: &VirtualMachine,
-) -> PyResult<Option<PyObjectRef>> {
-    if let Some(ref dict) = obj.dict {
-        dict.get_item_option(attr_name, vm)
-    } else {
-        Ok(None)
-    }
+    vm.generic_getattribute(obj.clone(), name.clone())?
+        .ok_or_else(|| vm.new_attribute_error(format!("{} has no attribute '{}'", obj, name)))
 }
diff --git a/vm/src/obj/objproperty.rs b/vm/src/obj/objproperty.rs
index 9bf213076..a6d5bcfa1 100644
--- a/vm/src/obj/objproperty.rs
+++ b/vm/src/obj/objproperty.rs
@@ -37,7 +37,7 @@ impl PyReadOnlyProperty {
         if obj.is(vm.ctx.none.as_object()) {
             Ok(zelf.into_object())
         } else {
-            vm.invoke(zelf.getter.clone(), obj)
+            vm.invoke(&zelf.getter, obj)
         }
     }
 }
@@ -123,8 +123,8 @@ impl PyProperty {
 
     // specialised version that doesn't check for None
     pub(crate) fn instance_binding_get(&self, obj: PyObjectRef, vm: &VirtualMachine) -> PyResult {
-        if let Some(getter) = self.getter.as_ref() {
-            vm.invoke(getter.clone(), obj)
+        if let Some(ref getter) = self.getter.as_ref() {
+            vm.invoke(getter, obj)
         } else {
             Err(vm.new_attribute_error("unreadable attribute".to_string()))
         }
@@ -141,7 +141,7 @@ impl PyProperty {
             if obj.is(vm.ctx.none.as_object()) {
                 Ok(zelf.into_object())
             } else {
-                vm.invoke(getter.clone(), obj)
+                vm.invoke(&getter, obj)
             }
         } else {
             Err(vm.new_attribute_error("unreadable attribute".to_string()))
@@ -150,8 +150,8 @@ impl PyProperty {
 
     #[pymethod(name = "__set__")]
     fn set(&self, obj: PyObjectRef, value: PyObjectRef, vm: &VirtualMachine) -> PyResult {
-        if let Some(setter) = self.setter.as_ref() {
-            vm.invoke(setter.clone(), vec![obj, value])
+        if let Some(ref setter) = self.setter.as_ref() {
+            vm.invoke(setter, vec![obj, value])
         } else {
             Err(vm.new_attribute_error("can't set attribute".to_string()))
         }
@@ -159,8 +159,8 @@ impl PyProperty {
 
     #[pymethod(name = "__delete__")]
     fn delete(&self, obj: PyObjectRef, vm: &VirtualMachine) -> PyResult {
-        if let Some(deleter) = self.deleter.as_ref() {
-            vm.invoke(deleter.clone(), obj)
+        if let Some(ref deleter) = self.deleter.as_ref() {
+            vm.invoke(deleter, obj)
         } else {
             Err(vm.new_attribute_error("can't delete attribute".to_string()))
         }
@@ -305,12 +305,12 @@ impl<'a> PropertyBuilder<'a> {
 }
 
 pub fn init(context: &PyContext) {
-    PyReadOnlyProperty::extend_class(context, &context.readonly_property_type);
-    PyProperty::extend_class(context, &context.property_type);
+    PyReadOnlyProperty::extend_class(context, &context.types.readonly_property_type);
+    PyProperty::extend_class(context, &context.types.property_type);
 
     // This is a bit unfortunate, but this instance attribute overlaps with the
     // class __doc__ string..
-    extend_class!(context, &context.property_type, {
+    extend_class!(context, &context.types.property_type, {
         "__doc__" =>
         PropertyBuilder::new(context)
             .add_getter(PyProperty::doc_getter)
diff --git a/vm/src/obj/objrange.rs b/vm/src/obj/objrange.rs
index 905550f50..99584a292 100644
--- a/vm/src/obj/objrange.rs
+++ b/vm/src/obj/objrange.rs
@@ -105,8 +105,8 @@ pub fn get_value(obj: &PyObjectRef) -> PyRange {
 }
 
 pub fn init(context: &PyContext) {
-    PyRange::extend_class(context, &context.range_type);
-    PyRangeIterator::extend_class(context, &context.rangeiterator_type);
+    PyRange::extend_class(context, &context.types.range_type);
+    PyRangeIterator::extend_class(context, &context.types.rangeiterator_type);
 }
 
 type PyRangeRef = PyRef<PyRange>;
diff --git a/vm/src/obj/objset.rs b/vm/src/obj/objset.rs
index cfa8e1701..dc4a3ca95 100644
--- a/vm/src/obj/objset.rs
+++ b/vm/src/obj/objset.rs
@@ -748,6 +748,6 @@ impl TryFromObject for SetIterable {
 }
 
 pub fn init(context: &PyContext) {
-    PySet::extend_class(context, &context.set_type);
-    PyFrozenSet::extend_class(context, &context.frozenset_type);
+    PySet::extend_class(context, &context.types.set_type);
+    PyFrozenSet::extend_class(context, &context.types.frozenset_type);
 }
diff --git a/vm/src/obj/objslice.rs b/vm/src/obj/objslice.rs
index 82e4cef8c..0de224d36 100644
--- a/vm/src/obj/objslice.rs
+++ b/vm/src/obj/objslice.rs
@@ -114,7 +114,7 @@ fn to_index_value(vm: &VirtualMachine, obj: &PyObjectRef) -> PyResult<Option<Big
 }
 
 pub fn init(context: &PyContext) {
-    let slice_type = &context.slice_type;
+    let slice_type = &context.types.slice_type;
 
     extend_class!(context, slice_type, {
         "__new__" => context.new_rustfunc(slice_new),
diff --git a/vm/src/obj/objstaticmethod.rs b/vm/src/obj/objstaticmethod.rs
index a33acf176..e330652a5 100644
--- a/vm/src/obj/objstaticmethod.rs
+++ b/vm/src/obj/objstaticmethod.rs
@@ -32,7 +32,7 @@ impl PyStaticMethodRef {
 }
 
 pub fn init(context: &PyContext) {
-    let staticmethod_type = &context.staticmethod_type;
+    let staticmethod_type = &context.types.staticmethod_type;
     extend_class!(context, staticmethod_type, {
         "__get__" => context.new_rustfunc(PyStaticMethodRef::get),
         "__new__" => context.new_rustfunc(PyStaticMethodRef::new),
diff --git a/vm/src/obj/objstr.rs b/vm/src/obj/objstr.rs
index 13e26ffd9..8f69fa749 100644
--- a/vm/src/obj/objstr.rs
+++ b/vm/src/obj/objstr.rs
@@ -1146,10 +1146,10 @@ impl IntoPyObject for &String {
 }
 
 pub fn init(ctx: &PyContext) {
-    PyString::extend_class(ctx, &ctx.str_type);
+    PyString::extend_class(ctx, &ctx.types.str_type);
 
-    PyStringIterator::extend_class(ctx, &ctx.striterator_type);
-    PyStringReverseIterator::extend_class(ctx, &ctx.strreverseiterator_type);
+    PyStringIterator::extend_class(ctx, &ctx.types.striterator_type);
+    PyStringReverseIterator::extend_class(ctx, &ctx.types.strreverseiterator_type);
 }
 
 pub fn get_value(obj: &PyObjectRef) -> String {
@@ -1328,9 +1328,9 @@ fn do_cformat(
     } else {
         // check for only literal parts, in which case only dict or empty tuple is allowed
         if num_specifiers == 0
-            && !(objtype::isinstance(&values_obj, &vm.ctx.tuple_type)
+            && !(objtype::isinstance(&values_obj, &vm.ctx.types.tuple_type)
                 && objtuple::get_value(&values_obj).is_empty())
-            && !objtype::isinstance(&values_obj, &vm.ctx.dict_type)
+            && !objtype::isinstance(&values_obj, &vm.ctx.types.dict_type)
         {
             return Err(vm.new_type_error(
                 "not all arguments converted during string formatting".to_string(),
@@ -1396,7 +1396,7 @@ fn do_cformat(
             .into_iter()
             .nth(tuple_index)
             .is_some())
-        && !objtype::isinstance(&values_obj, &vm.ctx.dict_type)
+        && !objtype::isinstance(&values_obj, &vm.ctx.types.dict_type)
     {
         return Err(
             vm.new_type_error("not all arguments converted during string formatting".to_string())
diff --git a/vm/src/obj/objsuper.rs b/vm/src/obj/objsuper.rs
index a9fb668cb..754fe93d5 100644
--- a/vm/src/obj/objsuper.rs
+++ b/vm/src/obj/objsuper.rs
@@ -33,7 +33,7 @@ impl PyValue for PySuper {
 }
 
 pub fn init(context: &PyContext) {
-    let super_type = &context.super_type;
+    let super_type = &context.types.super_type;
 
     let super_doc = "super() -> same as super(__class__, <first argument>)\n\
                      super(type) -> unbound super object\n\
diff --git a/vm/src/obj/objtuple.rs b/vm/src/obj/objtuple.rs
index 5be1232c0..459f0e9bc 100644
--- a/vm/src/obj/objtuple.rs
+++ b/vm/src/obj/objtuple.rs
@@ -276,7 +276,7 @@ impl PyTupleIterator {
 
 #[rustfmt::skip] // to avoid line splitting
 pub fn init(context: &PyContext) {
-    let tuple_type = &context.tuple_type;
+    let tuple_type = &context.types.tuple_type;
     let tuple_doc = "tuple() -> empty tuple
 tuple(iterable) -> tuple initialized from iterable's items
 
@@ -303,5 +303,5 @@ If the argument is a tuple, the return value is the same object.";
         "index" => context.new_rustfunc(PyTupleRef::index)
     });
 
-    PyTupleIterator::extend_class(context, &context.tupleiterator_type);
+    PyTupleIterator::extend_class(context, &context.types.tupleiterator_type);
 }
diff --git a/vm/src/obj/objtype.rs b/vm/src/obj/objtype.rs
index 9df1a829f..68b2feba6 100644
--- a/vm/src/obj/objtype.rs
+++ b/vm/src/obj/objtype.rs
@@ -137,7 +137,7 @@ impl PyClassRef {
         if let Some(attr) = class_get_attr(&mcl, &name) {
             let attr_class = attr.class();
             if class_has_attr(&attr_class, "__set__") {
-                if let Some(descriptor) = class_get_attr(&attr_class, "__get__") {
+                if let Some(ref descriptor) = class_get_attr(&attr_class, "__get__") {
                     return vm.invoke(
                         descriptor,
                         vec![attr, self.into_object(), mcl.into_object()],
@@ -148,7 +148,7 @@ impl PyClassRef {
 
         if let Some(attr) = class_get_attr(&self, &name) {
             let attr_class = attr.class();
-            if let Some(descriptor) = class_get_attr(&attr_class, "__get__") {
+            if let Some(ref descriptor) = class_get_attr(&attr_class, "__get__") {
                 let none = vm.get_none();
                 return vm.invoke(descriptor, vec![attr, none, self.into_object()]);
             }
@@ -158,7 +158,7 @@ impl PyClassRef {
             Ok(cls_attr)
         } else if let Some(attr) = class_get_attr(&mcl, &name) {
             vm.call_get_descriptor(attr, self.into_object())
-        } else if let Some(getter) = class_get_attr(&self, "__getattr__") {
+        } else if let Some(ref getter) = class_get_attr(&self, "__getattr__") {
             vm.invoke(getter, vec![mcl.into_object(), name_ref.into_object()])
         } else {
             Err(vm.new_attribute_error(format!("{} has no attribute '{}'", self, name)))
@@ -172,7 +172,7 @@ impl PyClassRef {
         vm: &VirtualMachine,
     ) -> PyResult<()> {
         if let Some(attr) = class_get_attr(&self.class(), &attr_name.value) {
-            if let Some(descriptor) = class_get_attr(&attr.class(), "__set__") {
+            if let Some(ref descriptor) = class_get_attr(&attr.class(), "__set__") {
                 vm.invoke(descriptor, vec![attr, self.into_object(), value])?;
                 return Ok(());
             }
@@ -212,7 +212,7 @@ pub fn init(ctx: &PyContext) {
                     type(object) -> the object's type\n\
                     type(name, bases, dict) -> a new type";
 
-    extend_class!(&ctx, &ctx.type_type, {
+    extend_class!(&ctx, &ctx.types.type_type, {
         "__call__" => ctx.new_rustfunc(type_call),
         "__dict__" =>
         PropertyBuilder::new(ctx)
@@ -288,11 +288,11 @@ pub fn type_call(class: PyClassRef, args: Args, kwargs: KwArgs, vm: &VirtualMach
     vm_trace!("type_call: {:?}", class);
     let new = class_get_attr(&class, "__new__").expect("All types should have a __new__.");
     let new_wrapped = vm.call_get_descriptor(new, class.into_object())?;
-    let obj = vm.invoke(new_wrapped, (&args, &kwargs))?;
+    let obj = vm.invoke(&new_wrapped, (&args, &kwargs))?;
 
     if let Some(init_method_or_err) = vm.get_method(obj.clone(), "__init__") {
         let init_method = init_method_or_err?;
-        let res = vm.invoke(init_method, (&args, &kwargs))?;
+        let res = vm.invoke(&init_method, (&args, &kwargs))?;
         if !res.is(&vm.get_none()) {
             return Err(vm.new_type_error("__init__ must return None".to_string()));
         }
@@ -433,8 +433,8 @@ mod tests {
     #[test]
     fn test_linearise() {
         let context = PyContext::new();
-        let object: PyClassRef = context.object.clone();
-        let type_type = &context.type_type;
+        let object: PyClassRef = context.object();
+        let type_type = &context.types.type_type;
 
         let a = new(type_type.clone(), "A", vec![object.clone()], HashMap::new()).unwrap();
         let b = new(type_type.clone(), "B", vec![object.clone()], HashMap::new()).unwrap();
diff --git a/vm/src/obj/objweakproxy.rs b/vm/src/obj/objweakproxy.rs
index 5d4f68d9d..f510a03ef 100644
--- a/vm/src/obj/objweakproxy.rs
+++ b/vm/src/obj/objweakproxy.rs
@@ -61,5 +61,5 @@ impl PyWeakProxy {
 }
 
 pub fn init(context: &PyContext) {
-    PyWeakProxy::extend_class(&context, &context.weakproxy_type);
+    PyWeakProxy::extend_class(&context, &context.types.weakproxy_type);
 }
diff --git a/vm/src/obj/objweakref.rs b/vm/src/obj/objweakref.rs
index b3b7e03c9..ae4375cd0 100644
--- a/vm/src/obj/objweakref.rs
+++ b/vm/src/obj/objweakref.rs
@@ -48,7 +48,7 @@ impl PyWeakRef {
 }
 
 pub fn init(context: &PyContext) {
-    extend_class!(context, &context.weakref_type, {
+    extend_class!(context, &context.types.weakref_type, {
         "__new__" => context.new_rustfunc(PyWeakRef::create),
         "__call__" => context.new_rustfunc(PyWeakRef::call)
     });
diff --git a/vm/src/obj/objzip.rs b/vm/src/obj/objzip.rs
index d9c577aa0..0223b8bf2 100644
--- a/vm/src/obj/objzip.rs
+++ b/vm/src/obj/objzip.rs
@@ -51,8 +51,8 @@ impl PyZip {
 }
 
 pub fn init(context: &PyContext) {
-    PyZip::extend_class(context, &context.zip_type);
-    extend_class!(context, &context.zip_type, {
+    PyZip::extend_class(context, &context.types.zip_type);
+    extend_class!(context, &context.types.zip_type, {
         "__new__" => context.new_rustfunc(zip_new),
     });
 }
diff --git a/vm/src/pyobject.rs b/vm/src/pyobject.rs
index ba40d5473..05049528c 100644
--- a/vm/src/pyobject.rs
+++ b/vm/src/pyobject.rs
@@ -1,12 +1,9 @@
 use std::any::Any;
 use std::cell::Cell;
-use std::cell::RefCell;
 use std::collections::HashMap;
 use std::fmt;
 use std::marker::PhantomData;
-use std::mem;
 use std::ops::Deref;
-use std::ptr;
 use std::rc::Rc;
 
 use num_bigint::BigInt;
@@ -16,46 +13,30 @@ use num_traits::{One, Zero};
 use crate::bytecode;
 use crate::exceptions;
 use crate::function::{IntoPyNativeFunc, PyFuncArgs};
-use crate::obj::objbool;
 use crate::obj::objbuiltinfunc::PyBuiltinFunction;
 use crate::obj::objbytearray;
 use crate::obj::objbytes;
-use crate::obj::objclassmethod::{self, PyClassMethod};
+use crate::obj::objclassmethod::PyClassMethod;
 use crate::obj::objcode;
 use crate::obj::objcode::PyCodeRef;
-use crate::obj::objcomplex::{self, PyComplex};
-use crate::obj::objdict::{self, PyDict, PyDictRef};
-use crate::obj::objellipsis;
-use crate::obj::objenumerate;
-use crate::obj::objfilter;
-use crate::obj::objfloat::{self, PyFloat};
-use crate::obj::objframe;
-use crate::obj::objfunction::{self, PyFunction, PyMethod};
-use crate::obj::objgenerator;
-use crate::obj::objint::{self, PyInt, PyIntRef};
+use crate::obj::objcomplex::PyComplex;
+use crate::obj::objdict::{PyDict, PyDictRef};
+use crate::obj::objfloat::PyFloat;
+use crate::obj::objfunction::{PyFunction, PyMethod};
+use crate::obj::objint::{PyInt, PyIntRef};
 use crate::obj::objiter;
-use crate::obj::objlist::{self, PyList};
-use crate::obj::objmap;
-use crate::obj::objmappingproxy;
-use crate::obj::objmemory;
-use crate::obj::objmodule::{self, PyModule};
-use crate::obj::objnamespace::{self, PyNamespace};
-use crate::obj::objnone::{self, PyNone, PyNoneRef};
+use crate::obj::objlist::PyList;
+use crate::obj::objmodule::PyModule;
+use crate::obj::objnamespace::PyNamespace;
+use crate::obj::objnone::{PyNone, PyNoneRef};
 use crate::obj::objobject;
-use crate::obj::objproperty;
 use crate::obj::objproperty::PropertyBuilder;
-use crate::obj::objrange;
-use crate::obj::objset::{self, PySet};
-use crate::obj::objslice;
-use crate::obj::objstaticmethod;
+use crate::obj::objset::PySet;
 use crate::obj::objstr;
-use crate::obj::objsuper;
-use crate::obj::objtuple::{self, PyTuple, PyTupleRef};
+use crate::obj::objtuple::{PyTuple, PyTupleRef};
 use crate::obj::objtype::{self, PyClass, PyClassRef};
-use crate::obj::objweakproxy;
-use crate::obj::objweakref;
-use crate::obj::objzip;
 use crate::scope::Scope;
+use crate::types::{create_type, initialize_types, TypeZoo};
 use crate::vm::VirtualMachine;
 use indexmap::IndexMap;
 
@@ -112,71 +93,16 @@ impl fmt::Display for PyObject<dyn PyObjectPayload> {
 
 #[derive(Debug)]
 pub struct PyContext {
-    pub bytes_type: PyClassRef,
-    pub bytesiterator_type: PyClassRef,
-    pub bytearray_type: PyClassRef,
-    pub bytearrayiterator_type: PyClassRef,
-    pub bool_type: PyClassRef,
-    pub classmethod_type: PyClassRef,
-    pub code_type: PyClassRef,
-    pub dict_type: PyClassRef,
-    pub ellipsis_type: PyClassRef,
-    pub enumerate_type: PyClassRef,
-    pub filter_type: PyClassRef,
-    pub float_type: PyClassRef,
-    pub frame_type: PyClassRef,
-    pub frozenset_type: PyClassRef,
-    pub generator_type: PyClassRef,
-    pub int_type: PyClassRef,
-    pub iter_type: PyClassRef,
-    pub complex_type: PyClassRef,
     pub true_value: PyIntRef,
     pub false_value: PyIntRef,
-    pub list_type: PyClassRef,
-    pub listiterator_type: PyClassRef,
-    pub listreverseiterator_type: PyClassRef,
-    pub striterator_type: PyClassRef,
-    pub strreverseiterator_type: PyClassRef,
-    pub dictkeyiterator_type: PyClassRef,
-    pub dictvalueiterator_type: PyClassRef,
-    pub dictitemiterator_type: PyClassRef,
-    pub dictkeys_type: PyClassRef,
-    pub dictvalues_type: PyClassRef,
-    pub dictitems_type: PyClassRef,
-    pub map_type: PyClassRef,
-    pub memoryview_type: PyClassRef,
     pub none: PyNoneRef,
+    pub empty_tuple: PyTupleRef,
+    pub ellipsis_type: PyClassRef,
     pub ellipsis: PyEllipsisRef,
     pub not_implemented: PyNotImplementedRef,
-    pub empty_tuple: PyTupleRef,
-    pub tuple_type: PyClassRef,
-    pub tupleiterator_type: PyClassRef,
-    pub set_type: PyClassRef,
-    pub staticmethod_type: PyClassRef,
-    pub super_type: PyClassRef,
-    pub str_type: PyClassRef,
-    pub range_type: PyClassRef,
-    pub rangeiterator_type: PyClassRef,
-    pub slice_type: PyClassRef,
-    pub type_type: PyClassRef,
-    pub zip_type: PyClassRef,
-    pub function_type: PyClassRef,
-    pub builtin_function_or_method_type: PyClassRef,
-    pub property_type: PyClassRef,
-    pub readonly_property_type: PyClassRef,
-    pub module_type: PyClassRef,
-    pub namespace_type: PyClassRef,
-    pub bound_method_type: PyClassRef,
-    pub weakref_type: PyClassRef,
-    pub weakproxy_type: PyClassRef,
-    pub mappingproxy_type: PyClassRef,
-    pub object: PyClassRef,
-    pub exceptions: exceptions::ExceptionZoo,
-}
 
-pub fn create_type(name: &str, type_type: &PyClassRef, base: &PyClassRef) -> PyClassRef {
-    let dict = PyAttributes::new();
-    objtype::new(type_type.clone(), name, vec![base.clone()], dict).unwrap()
+    pub types: TypeZoo,
+    pub exceptions: exceptions::ExceptionZoo,
 }
 
 pub type PyNotImplementedRef = PyRef<PyNotImplemented>;
@@ -201,115 +127,12 @@ impl PyValue for PyEllipsis {
     }
 }
 
-fn init_type_hierarchy() -> (PyClassRef, PyClassRef) {
-    // `type` inherits from `object`
-    // and both `type` and `object are instances of `type`.
-    // to produce this circular dependency, we need an unsafe block.
-    // (and yes, this will never get dropped. TODO?)
-    let (type_type, object_type) = unsafe {
-        let object_type = PyObject {
-            typ: mem::uninitialized(), // !
-            dict: None,
-            payload: PyClass {
-                name: String::from("object"),
-                mro: vec![],
-                subclasses: RefCell::new(vec![]),
-                attributes: RefCell::new(PyAttributes::new()),
-            },
-        }
-        .into_ref();
-
-        let type_type = PyObject {
-            typ: mem::uninitialized(), // !
-            dict: None,
-            payload: PyClass {
-                name: String::from("type"),
-                mro: vec![object_type.clone().downcast().unwrap()],
-                subclasses: RefCell::new(vec![]),
-                attributes: RefCell::new(PyAttributes::new()),
-            },
-        }
-        .into_ref();
-
-        let object_type_ptr = PyObjectRef::into_raw(object_type.clone()) as *mut PyObject<PyClass>;
-        let type_type_ptr = PyObjectRef::into_raw(type_type.clone()) as *mut PyObject<PyClass>;
-
-        let type_type: PyClassRef = type_type.downcast().unwrap();
-        let object_type: PyClassRef = object_type.downcast().unwrap();
-
-        ptr::write(&mut (*object_type_ptr).typ, type_type.clone());
-        ptr::write(&mut (*type_type_ptr).typ, type_type.clone());
-
-        (type_type, object_type)
-    };
-
-    object_type
-        .subclasses
-        .borrow_mut()
-        .push(objweakref::PyWeak::downgrade(&type_type.as_object()));
-
-    (type_type, object_type)
-}
-
 // Basic objects:
 impl PyContext {
     pub fn new() -> Self {
         flame_guard!("init PyContext");
-        let (type_type, object_type) = init_type_hierarchy();
-
-        let dict_type = create_type("dict", &type_type, &object_type);
-        let module_type = create_type("module", &type_type, &object_type);
-        let namespace_type = create_type("SimpleNamespace", &type_type, &object_type);
-        let classmethod_type = create_type("classmethod", &type_type, &object_type);
-        let staticmethod_type = create_type("staticmethod", &type_type, &object_type);
-        let function_type = create_type("function", &type_type, &object_type);
-        let builtin_function_or_method_type =
-            create_type("builtin_function_or_method", &type_type, &object_type);
-        let property_type = create_type("property", &type_type, &object_type);
-        let readonly_property_type = create_type("readonly_property", &type_type, &object_type);
-        let super_type = create_type("super", &type_type, &object_type);
-        let weakref_type = create_type("ref", &type_type, &object_type);
-        let weakproxy_type = create_type("weakproxy", &type_type, &object_type);
-        let generator_type = create_type("generator", &type_type, &object_type);
-        let bound_method_type = create_type("method", &type_type, &object_type);
-        let str_type = create_type("str", &type_type, &object_type);
-        let list_type = create_type("list", &type_type, &object_type);
-        let listiterator_type = create_type("list_iterator", &type_type, &object_type);
-        let listreverseiterator_type =
-            create_type("list_reverseiterator", &type_type, &object_type);
-        let striterator_type = create_type("str_iterator", &type_type, &object_type);
-        let strreverseiterator_type = create_type("str_reverseiterator", &type_type, &object_type);
-        let dictkeys_type = create_type("dict_keys", &type_type, &object_type);
-        let dictvalues_type = create_type("dict_values", &type_type, &object_type);
-        let dictitems_type = create_type("dict_items", &type_type, &object_type);
-        let dictkeyiterator_type = create_type("dict_keyiterator", &type_type, &object_type);
-        let dictvalueiterator_type = create_type("dict_valueiterator", &type_type, &object_type);
-        let dictitemiterator_type = create_type("dict_itemiterator", &type_type, &object_type);
-        let set_type = create_type("set", &type_type, &object_type);
-        let frozenset_type = create_type("frozenset", &type_type, &object_type);
-        let int_type = create_type("int", &type_type, &object_type);
-        let float_type = create_type("float", &type_type, &object_type);
-        let frame_type = create_type("frame", &type_type, &object_type);
-        let complex_type = create_type("complex", &type_type, &object_type);
-        let bytes_type = create_type("bytes", &type_type, &object_type);
-        let bytesiterator_type = create_type("bytes_iterator", &type_type, &object_type);
-        let bytearray_type = create_type("bytearray", &type_type, &object_type);
-        let bytearrayiterator_type = create_type("bytearray_iterator", &type_type, &object_type);
-        let tuple_type = create_type("tuple", &type_type, &object_type);
-        let tupleiterator_type = create_type("tuple_iterator", &type_type, &object_type);
-        let iter_type = create_type("iter", &type_type, &object_type);
-        let enumerate_type = create_type("enumerate", &type_type, &object_type);
-        let filter_type = create_type("filter", &type_type, &object_type);
-        let map_type = create_type("map", &type_type, &object_type);
-        let zip_type = create_type("zip", &type_type, &object_type);
-        let bool_type = create_type("bool", &type_type, &int_type);
-        let memoryview_type = create_type("memoryview", &type_type, &object_type);
-        let code_type = create_type("code", &type_type, &object_type);
-        let range_type = create_type("range", &type_type, &object_type);
-        let rangeiterator_type = create_type("range_iterator", &type_type, &object_type);
-        let slice_type = create_type("slice", &type_type, &object_type);
-        let mappingproxy_type = create_type("mappingproxy", &type_type, &object_type);
-        let exceptions = exceptions::ExceptionZoo::new(&type_type, &object_type);
+        let types = TypeZoo::new();
+        let exceptions = exceptions::ExceptionZoo::new(&types.type_type, &types.object_type);
 
         fn create_object<T: PyObjectPayload>(payload: T, cls: &PyClassRef) -> PyRef<T> {
             PyRef {
@@ -318,297 +141,213 @@ impl PyContext {
             }
         }
 
-        let none_type = create_type("NoneType", &type_type, &object_type);
+        let none_type = create_type("NoneType", &types.type_type, &types.object_type);
         let none = create_object(PyNone, &none_type);
 
-        let ellipsis_type = create_type("EllipsisType", &type_type, &object_type);
+        let ellipsis_type = create_type("EllipsisType", &types.type_type, &types.object_type);
         let ellipsis = create_object(PyEllipsis, &ellipsis_type);
 
-        let not_implemented_type = create_type("NotImplementedType", &type_type, &object_type);
+        let not_implemented_type =
+            create_type("NotImplementedType", &types.type_type, &types.object_type);
         let not_implemented = create_object(PyNotImplemented, &not_implemented_type);
 
-        let true_value = create_object(PyInt::new(BigInt::one()), &bool_type);
-        let false_value = create_object(PyInt::new(BigInt::zero()), &bool_type);
+        let true_value = create_object(PyInt::new(BigInt::one()), &types.bool_type);
+        let false_value = create_object(PyInt::new(BigInt::zero()), &types.bool_type);
 
-        let empty_tuple = create_object(PyTuple::from(vec![]), &tuple_type);
+        let empty_tuple = create_object(PyTuple::from(vec![]), &types.tuple_type);
 
         let context = PyContext {
-            bool_type,
-            memoryview_type,
-            bytearray_type,
-            bytearrayiterator_type,
-            bytes_type,
-            bytesiterator_type,
-            code_type,
-            complex_type,
-            classmethod_type,
-            int_type,
-            float_type,
-            frame_type,
-            staticmethod_type,
-            list_type,
-            listiterator_type,
-            listreverseiterator_type,
-            striterator_type,
-            strreverseiterator_type,
-            dictkeys_type,
-            dictvalues_type,
-            dictitems_type,
-            dictkeyiterator_type,
-            dictvalueiterator_type,
-            dictitemiterator_type,
-            set_type,
-            frozenset_type,
             true_value,
             false_value,
-            tuple_type,
-            tupleiterator_type,
-            iter_type,
-            ellipsis_type,
-            enumerate_type,
-            filter_type,
-            map_type,
-            zip_type,
-            dict_type,
+            not_implemented,
             none,
             ellipsis,
-            not_implemented,
-            str_type,
-            range_type,
-            rangeiterator_type,
-            slice_type,
-            object: object_type,
-            function_type,
-            builtin_function_or_method_type,
-            super_type,
-            mappingproxy_type,
-            property_type,
-            readonly_property_type,
-            generator_type,
-            module_type,
-            namespace_type,
-            bound_method_type,
-            weakref_type,
-            weakproxy_type,
-            type_type,
+            ellipsis_type,
+
+            types,
             exceptions,
             empty_tuple,
         };
-        objtype::init(&context);
-        objlist::init(&context);
-        objset::init(&context);
-        objtuple::init(&context);
-        objobject::init(&context);
-        objdict::init(&context);
-        objfunction::init(&context);
-        objstaticmethod::init(&context);
-        objclassmethod::init(&context);
-        objgenerator::init(&context);
-        objint::init(&context);
-        objfloat::init(&context);
-        objcomplex::init(&context);
-        objbytes::init(&context);
-        objbytearray::init(&context);
-        objproperty::init(&context);
-        objmemory::init(&context);
-        objstr::init(&context);
-        objrange::init(&context);
-        objslice::init(&context);
-        objsuper::init(&context);
-        objtuple::init(&context);
-        objiter::init(&context);
-        objellipsis::init(&context);
-        objenumerate::init(&context);
-        objfilter::init(&context);
-        objmap::init(&context);
-        objzip::init(&context);
-        objbool::init(&context);
-        objcode::init(&context);
-        objframe::init(&context);
-        objweakref::init(&context);
-        objweakproxy::init(&context);
-        objnone::init(&context);
-        objmodule::init(&context);
-        objnamespace::init(&context);
-        objmappingproxy::init(&context);
+        initialize_types(&context);
+
         exceptions::init(&context);
         context
     }
 
     pub fn bytearray_type(&self) -> PyClassRef {
-        self.bytearray_type.clone()
+        self.types.bytearray_type.clone()
     }
 
     pub fn bytearrayiterator_type(&self) -> PyClassRef {
-        self.bytearrayiterator_type.clone()
+        self.types.bytearrayiterator_type.clone()
     }
 
     pub fn bytes_type(&self) -> PyClassRef {
-        self.bytes_type.clone()
+        self.types.bytes_type.clone()
     }
 
     pub fn bytesiterator_type(&self) -> PyClassRef {
-        self.bytesiterator_type.clone()
+        self.types.bytesiterator_type.clone()
     }
 
     pub fn code_type(&self) -> PyClassRef {
-        self.code_type.clone()
+        self.types.code_type.clone()
     }
 
     pub fn complex_type(&self) -> PyClassRef {
-        self.complex_type.clone()
+        self.types.complex_type.clone()
     }
 
     pub fn dict_type(&self) -> PyClassRef {
-        self.dict_type.clone()
+        self.types.dict_type.clone()
     }
 
     pub fn float_type(&self) -> PyClassRef {
-        self.float_type.clone()
+        self.types.float_type.clone()
     }
 
     pub fn frame_type(&self) -> PyClassRef {
-        self.frame_type.clone()
+        self.types.frame_type.clone()
     }
 
     pub fn int_type(&self) -> PyClassRef {
-        self.int_type.clone()
+        self.types.int_type.clone()
     }
 
     pub fn list_type(&self) -> PyClassRef {
-        self.list_type.clone()
+        self.types.list_type.clone()
     }
 
     pub fn listiterator_type(&self) -> PyClassRef {
-        self.listiterator_type.clone()
+        self.types.listiterator_type.clone()
     }
 
     pub fn listreverseiterator_type(&self) -> PyClassRef {
-        self.listreverseiterator_type.clone()
+        self.types.listreverseiterator_type.clone()
     }
 
     pub fn striterator_type(&self) -> PyClassRef {
-        self.striterator_type.clone()
+        self.types.striterator_type.clone()
     }
 
     pub fn strreverseiterator_type(&self) -> PyClassRef {
-        self.strreverseiterator_type.clone()
+        self.types.strreverseiterator_type.clone()
     }
 
     pub fn module_type(&self) -> PyClassRef {
-        self.module_type.clone()
+        self.types.module_type.clone()
     }
 
     pub fn namespace_type(&self) -> PyClassRef {
-        self.namespace_type.clone()
+        self.types.namespace_type.clone()
     }
 
     pub fn set_type(&self) -> PyClassRef {
-        self.set_type.clone()
+        self.types.set_type.clone()
     }
 
     pub fn range_type(&self) -> PyClassRef {
-        self.range_type.clone()
+        self.types.range_type.clone()
     }
 
     pub fn rangeiterator_type(&self) -> PyClassRef {
-        self.rangeiterator_type.clone()
+        self.types.rangeiterator_type.clone()
     }
 
     pub fn slice_type(&self) -> PyClassRef {
-        self.slice_type.clone()
+        self.types.slice_type.clone()
     }
 
     pub fn frozenset_type(&self) -> PyClassRef {
-        self.frozenset_type.clone()
+        self.types.frozenset_type.clone()
     }
 
     pub fn bool_type(&self) -> PyClassRef {
-        self.bool_type.clone()
+        self.types.bool_type.clone()
     }
 
     pub fn memoryview_type(&self) -> PyClassRef {
-        self.memoryview_type.clone()
+        self.types.memoryview_type.clone()
     }
 
     pub fn tuple_type(&self) -> PyClassRef {
-        self.tuple_type.clone()
+        self.types.tuple_type.clone()
     }
 
     pub fn tupleiterator_type(&self) -> PyClassRef {
-        self.tupleiterator_type.clone()
+        self.types.tupleiterator_type.clone()
     }
 
     pub fn iter_type(&self) -> PyClassRef {
-        self.iter_type.clone()
+        self.types.iter_type.clone()
     }
 
     pub fn enumerate_type(&self) -> PyClassRef {
-        self.enumerate_type.clone()
+        self.types.enumerate_type.clone()
     }
 
     pub fn filter_type(&self) -> PyClassRef {
-        self.filter_type.clone()
+        self.types.filter_type.clone()
     }
 
     pub fn map_type(&self) -> PyClassRef {
-        self.map_type.clone()
+        self.types.map_type.clone()
     }
 
     pub fn zip_type(&self) -> PyClassRef {
-        self.zip_type.clone()
+        self.types.zip_type.clone()
     }
 
     pub fn str_type(&self) -> PyClassRef {
-        self.str_type.clone()
+        self.types.str_type.clone()
     }
 
     pub fn super_type(&self) -> PyClassRef {
-        self.super_type.clone()
+        self.types.super_type.clone()
     }
 
     pub fn function_type(&self) -> PyClassRef {
-        self.function_type.clone()
+        self.types.function_type.clone()
     }
 
     pub fn builtin_function_or_method_type(&self) -> PyClassRef {
-        self.builtin_function_or_method_type.clone()
+        self.types.builtin_function_or_method_type.clone()
     }
 
     pub fn property_type(&self) -> PyClassRef {
-        self.property_type.clone()
+        self.types.property_type.clone()
     }
 
     pub fn readonly_property_type(&self) -> PyClassRef {
-        self.readonly_property_type.clone()
+        self.types.readonly_property_type.clone()
     }
 
     pub fn classmethod_type(&self) -> PyClassRef {
-        self.classmethod_type.clone()
+        self.types.classmethod_type.clone()
     }
 
     pub fn staticmethod_type(&self) -> PyClassRef {
-        self.staticmethod_type.clone()
+        self.types.staticmethod_type.clone()
     }
 
     pub fn generator_type(&self) -> PyClassRef {
-        self.generator_type.clone()
+        self.types.generator_type.clone()
     }
 
     pub fn bound_method_type(&self) -> PyClassRef {
-        self.bound_method_type.clone()
+        self.types.bound_method_type.clone()
     }
 
     pub fn weakref_type(&self) -> PyClassRef {
-        self.weakref_type.clone()
+        self.types.weakref_type.clone()
     }
 
     pub fn weakproxy_type(&self) -> PyClassRef {
-        self.weakproxy_type.clone()
+        self.types.weakproxy_type.clone()
     }
 
     pub fn type_type(&self) -> PyClassRef {
-        self.type_type.clone()
+        self.types.type_type.clone()
     }
 
     pub fn none(&self) -> PyObjectRef {
@@ -624,7 +363,7 @@ impl PyContext {
     }
 
     pub fn object(&self) -> PyClassRef {
-        self.object.clone()
+        self.types.object_type.clone()
     }
 
     pub fn new_int<T: Into<BigInt>>(&self, i: T) -> PyObjectRef {
@@ -691,16 +430,6 @@ impl PyContext {
         objtype::new(self.type_type(), name, vec![base], PyAttributes::new()).unwrap()
     }
 
-    pub fn new_module(&self, name: &str, dict: PyDictRef) -> PyObjectRef {
-        PyObject::new(
-            PyModule {
-                name: name.to_string(),
-            },
-            self.module_type.clone(),
-            Some(dict),
-        )
-    }
-
     pub fn new_namespace(&self) -> PyObjectRef {
         PyObject::new(PyNamespace, self.namespace_type(), Some(self.new_dict()))
     }
@@ -948,7 +677,7 @@ pub struct PyCallable {
 impl PyCallable {
     #[inline]
     pub fn invoke(&self, args: impl Into<PyFuncArgs>, vm: &VirtualMachine) -> PyResult {
-        vm.invoke(self.obj.clone(), args)
+        vm.invoke(&self.obj, args)
     }
 
     #[inline]
@@ -1103,8 +832,9 @@ impl<T> PyIterable<T> {
     /// This operation may fail if an exception is raised while invoking the
     /// `__iter__` method of the iterable object.
     pub fn iter<'a>(&self, vm: &'a VirtualMachine) -> PyResult<PyIterator<'a, T>> {
+        let method = &self.method;
         let iter_obj = vm.invoke(
-            self.method.clone(),
+            method,
             PyFuncArgs {
                 args: vec![],
                 kwargs: IndexMap::new(),
diff --git a/vm/src/stdlib/errno.rs b/vm/src/stdlib/errno.rs
index 0a8587087..6f82351f2 100644
--- a/vm/src/stdlib/errno.rs
+++ b/vm/src/stdlib/errno.rs
@@ -149,6 +149,96 @@ const ERROR_CODES: &[(&str, i32)] = &[
     ("ERFKILL", libc::ERFKILL),
 ];
 
+#[cfg(all(unix, not(target_os = "linux")))]
+const ERROR_CODES: &[(&str, i32)] = &[
+    ("ENODEV", libc::ENODEV),
+    ("EHOSTUNREACH", libc::EHOSTUNREACH),
+    ("ENOMSG", libc::ENOMSG),
+    ("ENODATA", libc::ENODATA),
+    ("ENOTBLK", libc::ENOTBLK),
+    ("ENOSYS", libc::ENOSYS),
+    ("EPIPE", libc::EPIPE),
+    ("EINVAL", libc::EINVAL),
+    ("EOVERFLOW", libc::EOVERFLOW),
+    ("EINTR", libc::EINTR),
+    ("EUSERS", libc::EUSERS),
+    ("ENOTEMPTY", libc::ENOTEMPTY),
+    ("ENOBUFS", libc::ENOBUFS),
+    ("EPROTO", libc::EPROTO),
+    ("EREMOTE", libc::EREMOTE),
+    ("ECHILD", libc::ECHILD),
+    ("ELOOP", libc::ELOOP),
+    ("EXDEV", libc::EXDEV),
+    ("E2BIG", libc::E2BIG),
+    ("ESRCH", libc::ESRCH),
+    ("EMSGSIZE", libc::EMSGSIZE),
+    ("EAFNOSUPPORT", libc::EAFNOSUPPORT),
+    ("EHOSTDOWN", libc::EHOSTDOWN),
+    ("EPFNOSUPPORT", libc::EPFNOSUPPORT),
+    ("ENOPROTOOPT", libc::ENOPROTOOPT),
+    ("EBUSY", libc::EBUSY),
+    ("EAGAIN", libc::EAGAIN),
+    ("EISCONN", libc::EISCONN),
+    ("ESHUTDOWN", libc::ESHUTDOWN),
+    ("EBADF", libc::EBADF),
+    ("EMULTIHOP", libc::EMULTIHOP),
+    ("EIO", libc::EIO),
+    ("EPROTOTYPE", libc::EPROTOTYPE),
+    ("ENOSPC", libc::ENOSPC),
+    ("ENOEXEC", libc::ENOEXEC),
+    ("EALREADY", libc::EALREADY),
+    ("ENETDOWN", libc::ENETDOWN),
+    ("EACCES", libc::EACCES),
+    ("EILSEQ", libc::EILSEQ),
+    ("ENOTDIR", libc::ENOTDIR),
+    ("EPERM", libc::EPERM),
+    ("EDOM", libc::EDOM),
+    ("ECONNREFUSED", libc::ECONNREFUSED),
+    ("EISDIR", libc::EISDIR),
+    ("EPROTONOSUPPORT", libc::EPROTONOSUPPORT),
+    ("EROFS", libc::EROFS),
+    ("EADDRNOTAVAIL", libc::EADDRNOTAVAIL),
+    ("EIDRM", libc::EIDRM),
+    ("EBADMSG", libc::EBADMSG),
+    ("ENFILE", libc::ENFILE),
+    ("ESPIPE", libc::ESPIPE),
+    ("ENOLINK", libc::ENOLINK),
+    ("ENETRESET", libc::ENETRESET),
+    ("ETIMEDOUT", libc::ETIMEDOUT),
+    ("ENOENT", libc::ENOENT),
+    ("EEXIST", libc::EEXIST),
+    ("EDQUOT", libc::EDQUOT),
+    ("ENOSTR", libc::ENOSTR),
+    ("EFAULT", libc::EFAULT),
+    ("EFBIG", libc::EFBIG),
+    ("ENOTCONN", libc::ENOTCONN),
+    ("EDESTADDRREQ", libc::EDESTADDRREQ),
+    ("ENOLCK", libc::ENOLCK),
+    ("ECONNABORTED", libc::ECONNABORTED),
+    ("ENETUNREACH", libc::ENETUNREACH),
+    ("ESTALE", libc::ESTALE),
+    ("ENOSR", libc::ENOSR),
+    ("ENOMEM", libc::ENOMEM),
+    ("ENOTSOCK", libc::ENOTSOCK),
+    ("EMLINK", libc::EMLINK),
+    ("ERANGE", libc::ERANGE),
+    ("ECONNRESET", libc::ECONNRESET),
+    ("EADDRINUSE", libc::EADDRINUSE),
+    ("ENOTSUP", libc::ENOTSUP),
+    ("ENAMETOOLONG", libc::ENAMETOOLONG),
+    ("ENOTTY", libc::ENOTTY),
+    ("ESOCKTNOSUPPORT", libc::ESOCKTNOSUPPORT),
+    ("ETIME", libc::ETIME),
+    ("ETOOMANYREFS", libc::ETOOMANYREFS),
+    ("EMFILE", libc::EMFILE),
+    ("ETXTBSY", libc::ETXTBSY),
+    ("EINPROGRESS", libc::EINPROGRESS),
+    ("ENXIO", libc::ENXIO),
+    ("ECANCELED", libc::ECANCELED),
+    ("EOWNERDEAD", libc::EOWNERDEAD),
+    ("ENOTRECOVERABLE", libc::ENOTRECOVERABLE),
+];
+
 #[cfg(windows)]
 const ERROR_CODES: &[(&str, i32)] = &[
     ("ENODEV", 19),
@@ -254,5 +344,5 @@ const ERROR_CODES: &[(&str, i32)] = &[
     ("ENOTSUP", 129),
 ];
 
-#[cfg(not(any(target_os = "linux", windows)))]
+#[cfg(not(any(unix, windows)))]
 const ERROR_CODES: &[(&str, i32)] = &[];
diff --git a/vm/src/stdlib/functools.rs b/vm/src/stdlib/functools.rs
new file mode 100644
index 000000000..a35bede73
--- /dev/null
+++ b/vm/src/stdlib/functools.rs
@@ -0,0 +1,46 @@
+use crate::function::OptionalArg;
+use crate::obj::objiter;
+use crate::obj::objtype;
+use crate::pyobject::{PyObjectRef, PyResult};
+use crate::vm::VirtualMachine;
+
+pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
+    let ctx = &vm.ctx;
+
+    py_module!(vm, "_functools", {
+        "reduce" => ctx.new_rustfunc(functools_reduce),
+    })
+}
+
+fn functools_reduce(
+    function: PyObjectRef,
+    sequence: PyObjectRef,
+    start_value: OptionalArg<PyObjectRef>,
+    vm: &VirtualMachine,
+) -> PyResult {
+    let iterator = objiter::get_iter(vm, &sequence)?;
+
+    let start_value = if let OptionalArg::Present(val) = start_value {
+        val
+    } else {
+        objiter::call_next(vm, &iterator).map_err(|err| {
+            if objtype::isinstance(&err, &vm.ctx.exceptions.stop_iteration) {
+                let exc_type = vm.ctx.exceptions.type_error.clone();
+                vm.new_exception(
+                    exc_type,
+                    "reduce() of empty sequence with no initial value".to_string(),
+                )
+            } else {
+                err
+            }
+        })?
+    };
+
+    let mut accumulator = start_value;
+
+    while let Ok(next_obj) = objiter::call_next(vm, &iterator) {
+        accumulator = vm.invoke(&function, vec![accumulator, next_obj])?
+    }
+
+    Ok(accumulator)
+}
diff --git a/vm/src/stdlib/io.rs b/vm/src/stdlib/io.rs
index 41c451f79..1178724f4 100644
--- a/vm/src/stdlib/io.rs
+++ b/vm/src/stdlib/io.rs
@@ -431,6 +431,31 @@ fn file_io_write(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
     }
 }
 
+#[cfg(windows)]
+fn file_io_close(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
+    use std::os::windows::io::IntoRawHandle;
+    arg_check!(vm, args, required = [(file_io, None)]);
+    let file_no = vm.get_attribute(file_io.clone(), "fileno")?;
+    let raw_fd = objint::get_value(&file_no).to_i64().unwrap();
+    let handle = os::rust_file(raw_fd);
+    let raw_handle = handle.into_raw_handle();
+    unsafe {
+        kernel32::CloseHandle(raw_handle);
+    }
+    Ok(vm.ctx.none())
+}
+
+#[cfg(unix)]
+fn file_io_close(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
+    arg_check!(vm, args, required = [(file_io, None)]);
+    let file_no = vm.get_attribute(file_io.clone(), "fileno")?;
+    let raw_fd = objint::get_value(&file_no).to_i32().unwrap();
+    unsafe {
+        libc::close(raw_fd);
+    }
+    Ok(vm.ctx.none())
+}
+
 fn file_io_seekable(vm: &VirtualMachine, _args: PyFuncArgs) -> PyResult {
     Ok(vm.ctx.new_bool(true))
 }
@@ -607,7 +632,7 @@ pub fn io_open(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
     // This is subsequently consumed by a Buffered Class.
     let file_io_class = vm.get_attribute(io_module.clone(), "FileIO").unwrap();
     let file_io_obj = vm.invoke(
-        file_io_class,
+        &file_io_class,
         vec![file.clone(), vm.ctx.new_str(mode.clone())],
     )?;
 
@@ -620,13 +645,13 @@ pub fn io_open(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
             let buffered_writer_class = vm
                 .get_attribute(io_module.clone(), "BufferedWriter")
                 .unwrap();
-            vm.invoke(buffered_writer_class, vec![file_io_obj.clone()])
+            vm.invoke(&buffered_writer_class, vec![file_io_obj.clone()])
         }
         'r' => {
             let buffered_reader_class = vm
                 .get_attribute(io_module.clone(), "BufferedReader")
                 .unwrap();
-            vm.invoke(buffered_reader_class, vec![file_io_obj.clone()])
+            vm.invoke(&buffered_reader_class, vec![file_io_obj.clone()])
         }
         //TODO: updating => PyBufferedRandom
         _ => unimplemented!("'a' mode is not yet implemented"),
@@ -637,7 +662,7 @@ pub fn io_open(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
         // a TextIOWrapper which is subsequently returned.
         't' => {
             let text_io_wrapper_class = vm.get_attribute(io_module, "TextIOWrapper").unwrap();
-            vm.invoke(text_io_wrapper_class, vec![buffered.unwrap()])
+            vm.invoke(&text_io_wrapper_class, vec![buffered.unwrap()])
         }
         // If the mode is binary this Buffered class is returned directly at
         // this point.
@@ -678,6 +703,7 @@ pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
         "read" => ctx.new_rustfunc(file_io_read),
         "readinto" => ctx.new_rustfunc(file_io_readinto),
         "write" => ctx.new_rustfunc(file_io_write),
+        "close" => ctx.new_rustfunc(file_io_close),
         "seekable" => ctx.new_rustfunc(file_io_seekable)
     });
 
diff --git a/vm/src/stdlib/itertools.rs b/vm/src/stdlib/itertools.rs
index 732020480..6039c178a 100644
--- a/vm/src/stdlib/itertools.rs
+++ b/vm/src/stdlib/itertools.rs
@@ -218,8 +218,9 @@ impl PyItertoolsStarmap {
     #[pymethod(name = "__next__")]
     fn next(&self, vm: &VirtualMachine) -> PyResult {
         let obj = call_next(vm, &self.iter)?;
+        let function = &self.function;
 
-        vm.invoke(self.function.clone(), vm.extract_elements(&obj)?)
+        vm.invoke(function, vm.extract_elements(&obj)?)
     }
 
     #[pymethod(name = "__iter__")]
@@ -271,8 +272,9 @@ impl PyItertoolsTakewhile {
 
         // might be StopIteration or anything else, which is propaged upwwards
         let obj = call_next(vm, &self.iterable)?;
+        let predicate = &self.predicate;
 
-        let verdict = vm.invoke(self.predicate.clone(), vec![obj.clone()])?;
+        let verdict = vm.invoke(predicate, vec![obj.clone()])?;
         let verdict = objbool::boolval(vm, verdict)?;
         if verdict {
             Ok(obj)
diff --git a/vm/src/stdlib/json.rs b/vm/src/stdlib/json.rs
index 8b5d21b75..aa3fb8157 100644
--- a/vm/src/stdlib/json.rs
+++ b/vm/src/stdlib/json.rs
@@ -1,6 +1,7 @@
 use crate::obj::objstr::PyStringRef;
 use crate::py_serde;
-use crate::pyobject::{create_type, ItemProtocol, PyObjectRef, PyResult};
+use crate::pyobject::{ItemProtocol, PyObjectRef, PyResult};
+use crate::types::create_type;
 use crate::VirtualMachine;
 use serde_json;
 
@@ -10,6 +11,12 @@ pub fn json_dumps(obj: PyObjectRef, vm: &VirtualMachine) -> PyResult<String> {
     serde_json::to_string(&serializer).map_err(|err| vm.new_type_error(err.to_string()))
 }
 
+pub fn json_dump(obj: PyObjectRef, fs: PyObjectRef, vm: &VirtualMachine) -> PyResult {
+    let result = json_dumps(obj, vm)?;
+    vm.call_method(&fs, "write", vec![vm.new_str(result)])?;
+    Ok(vm.get_none())
+}
+
 /// Implement json.loads
 pub fn json_loads(string: PyStringRef, vm: &VirtualMachine) -> PyResult {
     // TODO: Implement non-trivial deserialization case
@@ -33,19 +40,26 @@ pub fn json_loads(string: PyStringRef, vm: &VirtualMachine) -> PyResult {
     })
 }
 
+pub fn json_load(fp: PyObjectRef, vm: &VirtualMachine) -> PyResult {
+    let result = vm.call_method(&fp, "read", vec![])?;
+    json_loads(result.downcast()?, vm)
+}
+
 pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
     let ctx = &vm.ctx;
 
     // TODO: Make this a proper type with a constructor
     let json_decode_error = create_type(
         "JSONDecodeError",
-        &ctx.type_type,
+        &ctx.types.type_type,
         &ctx.exceptions.exception_type,
     );
 
     py_module!(vm, "json", {
         "dumps" => ctx.new_rustfunc(json_dumps),
+        "dump" => ctx.new_rustfunc(json_dump),
         "loads" => ctx.new_rustfunc(json_loads),
+        "load" => ctx.new_rustfunc(json_load),
         "JSONDecodeError" => json_decode_error
     })
 }
diff --git a/vm/src/stdlib/marshal.rs b/vm/src/stdlib/marshal.rs
index e7afc86d2..86f542ff6 100644
--- a/vm/src/stdlib/marshal.rs
+++ b/vm/src/stdlib/marshal.rs
@@ -1,17 +1,17 @@
 use crate::bytecode;
 use crate::obj::objbytes::{PyBytes, PyBytesRef};
 use crate::obj::objcode::{PyCode, PyCodeRef};
-use crate::pyobject::{IntoPyObject, PyObjectRef, PyResult};
+use crate::pyobject::{PyObjectRef, PyResult};
 use crate::vm::VirtualMachine;
 
-fn marshal_dumps(co: PyCodeRef, vm: &VirtualMachine) -> PyResult {
-    PyBytes::new(bincode::serialize(&co.code).unwrap()).into_pyobject(vm)
+fn marshal_dumps(co: PyCodeRef, _vm: &VirtualMachine) -> PyBytes {
+    PyBytes::new(bincode::serialize(&co.code).unwrap())
 }
 
-fn marshal_loads(code_bytes: PyBytesRef, vm: &VirtualMachine) -> PyResult {
-    let code = bincode::deserialize::<bytecode::CodeObject>(&code_bytes).unwrap();
-    let pycode = PyCode { code };
-    pycode.into_pyobject(vm)
+fn marshal_loads(code_bytes: PyBytesRef, vm: &VirtualMachine) -> PyResult<PyCode> {
+    let code = bincode::deserialize::<bytecode::CodeObject>(&code_bytes)
+        .map_err(|_| vm.new_value_error("Couldn't deserialize python bytecode".to_owned()))?;
+    Ok(PyCode { code })
 }
 
 pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
@@ -19,6 +19,6 @@ pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
 
     py_module!(vm, "marshal", {
         "loads" => ctx.new_rustfunc(marshal_loads),
-        "dumps" => ctx.new_rustfunc(marshal_dumps)
+        "dumps" => ctx.new_rustfunc(marshal_dumps),
     })
 }
diff --git a/vm/src/stdlib/math.rs b/vm/src/stdlib/math.rs
index 36dad8bca..3c2779f1e 100644
--- a/vm/src/stdlib/math.rs
+++ b/vm/src/stdlib/math.rs
@@ -181,7 +181,7 @@ fn try_magic_method(func_name: &str, vm: &VirtualMachine, value: &PyObjectRef) -
             func_name,
         )
     })?;
-    vm.invoke(method, vec![])
+    vm.invoke(&method, vec![])
 }
 
 fn math_trunc(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
@@ -191,7 +191,7 @@ fn math_trunc(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
 
 fn math_ceil(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(vm, args, required = [(value, None)]);
-    if objtype::isinstance(value, &vm.ctx.float_type) {
+    if objtype::isinstance(value, &vm.ctx.float_type()) {
         let v = objfloat::get_value(value);
         Ok(vm.ctx.new_float(v.ceil()))
     } else {
@@ -201,7 +201,7 @@ fn math_ceil(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
 
 fn math_floor(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(vm, args, required = [(value, None)]);
-    if objtype::isinstance(value, &vm.ctx.float_type) {
+    if objtype::isinstance(value, &vm.ctx.float_type()) {
         let v = objfloat::get_value(value);
         Ok(vm.ctx.new_float(v.floor()))
     } else {
diff --git a/vm/src/stdlib/mod.rs b/vm/src/stdlib/mod.rs
index 51ab96e52..076274dc3 100644
--- a/vm/src/stdlib/mod.rs
+++ b/vm/src/stdlib/mod.rs
@@ -5,6 +5,7 @@ mod codecs;
 mod collections;
 mod dis;
 mod errno;
+mod functools;
 mod hashlib;
 mod imp;
 mod itertools;
@@ -57,6 +58,7 @@ pub fn get_module_inits() -> HashMap<String, StdlibInitFunc> {
         "dis".to_string() => Box::new(dis::make_module),
         "_codecs".to_string() => Box::new(codecs::make_module),
         "_collections".to_string() => Box::new(collections::make_module),
+        "_functools".to_string() => Box::new(functools::make_module),
         "errno".to_string() => Box::new(errno::make_module),
         "hashlib".to_string() => Box::new(hashlib::make_module),
         "itertools".to_string() => Box::new(itertools::make_module),
diff --git a/vm/src/stdlib/os.rs b/vm/src/stdlib/os.rs
index aec771841..d0f1c4fe6 100644
--- a/vm/src/stdlib/os.rs
+++ b/vm/src/stdlib/os.rs
@@ -316,6 +316,15 @@ fn _os_environ(vm: &VirtualMachine) -> PyDictRef {
     environ
 }
 
+fn os_readlink(path: PyStringRef, dir_fd: DirFd, vm: &VirtualMachine) -> PyResult {
+    let path = make_path(vm, path, &dir_fd);
+    let path = fs::read_link(path.as_str()).map_err(|err| convert_io_error(vm, err))?;
+    let path = path.into_os_string().into_string().map_err(|_osstr| {
+        vm.new_unicode_decode_error("Can't convert OS path to valid UTF-8 string".into())
+    })?;
+    Ok(vm.ctx.new_str(path))
+}
+
 #[derive(Debug)]
 struct DirEntry {
     entry: fs::DirEntry,
@@ -964,7 +973,7 @@ pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
         // mkfifo Some Some None
         // mknod Some Some None
         // pathconf Some None None
-        // readlink Some Some None
+        SupportFunc::new(vm, "readlink", os_readlink, Some(false), Some(false), None),
         SupportFunc::new(vm, "remove", os_remove, Some(false), Some(false), None),
         SupportFunc::new(vm, "rename", os_rename, Some(false), Some(false), None),
         SupportFunc::new(vm, "replace", os_rename, Some(false), Some(false), None), // TODO: Fix replace
diff --git a/vm/src/stdlib/signal.rs b/vm/src/stdlib/signal.rs
index d72085ea0..2950282b1 100644
--- a/vm/src/stdlib/signal.rs
+++ b/vm/src/stdlib/signal.rs
@@ -92,7 +92,7 @@ pub fn check_signals(vm: &VirtualMachine) {
                 .get(&(signum as i32))
                 .expect("Handler should be set")
                 .clone();
-            vm.invoke(handler, vec![vm.new_int(signum), vm.get_none()])
+            vm.invoke(&handler, vec![vm.new_int(signum), vm.get_none()])
                 .expect("Test");
         }
     }
diff --git a/vm/src/stdlib/socket.rs b/vm/src/stdlib/socket.rs
index 9040c14ff..1a111d7ea 100644
--- a/vm/src/stdlib/socket.rs
+++ b/vm/src/stdlib/socket.rs
@@ -21,6 +21,7 @@ use crate::vm::VirtualMachine;
 use crate::obj::objtype::PyClassRef;
 #[cfg(unix)]
 use crate::stdlib::os::convert_nix_error;
+use num_bigint::Sign;
 use num_traits::ToPrimitive;
 
 #[derive(Debug, Copy, Clone)]
@@ -409,6 +410,17 @@ fn socket_inet_ntoa(packed_ip: PyBytesRef, vm: &VirtualMachine) -> PyResult {
     Ok(vm.new_str(Ipv4Addr::from(ip_num).to_string()))
 }
 
+fn socket_htonl(host: PyIntRef, vm: &VirtualMachine) -> PyResult {
+    if host.as_bigint().sign() == Sign::Minus {
+        return Err(
+            vm.new_overflow_error("can't convert negative value to unsigned int".to_string())
+        );
+    }
+
+    let host = host.as_bigint().to_u32().unwrap();
+    Ok(vm.new_int(host.to_be()))
+}
+
 pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
     let ctx = &vm.ctx;
 
@@ -435,6 +447,7 @@ pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
          "inet_aton" => ctx.new_rustfunc(socket_inet_aton),
          "inet_ntoa" => ctx.new_rustfunc(socket_inet_ntoa),
          "gethostname" => ctx.new_rustfunc(socket_gethostname),
+         "htonl" => ctx.new_rustfunc(socket_htonl),
     });
 
     extend_module_platform_specific(vm, module)
diff --git a/vm/src/stdlib/thread.rs b/vm/src/stdlib/thread.rs
index 414e7d72e..225001c4d 100644
--- a/vm/src/stdlib/thread.rs
+++ b/vm/src/stdlib/thread.rs
@@ -37,7 +37,7 @@ fn get_ident(_vm: &VirtualMachine) -> u32 {
 
 fn allocate_lock(vm: &VirtualMachine) -> PyResult {
     let lock_class = vm.class("_thread", "RLock");
-    vm.invoke(lock_class.into_object(), vec![])
+    vm.invoke(&lock_class.into_object(), vec![])
 }
 
 pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
diff --git a/vm/src/stdlib/zlib.rs b/vm/src/stdlib/zlib.rs
index b54d82425..59ccf0b8e 100644
--- a/vm/src/stdlib/zlib.rs
+++ b/vm/src/stdlib/zlib.rs
@@ -1,6 +1,7 @@
 use crate::function::OptionalArg;
 use crate::obj::{objbytes::PyBytesRef, objint::PyIntRef};
-use crate::pyobject::{create_type, ItemProtocol, PyObjectRef, PyResult};
+use crate::pyobject::{ItemProtocol, PyObjectRef, PyResult};
+use crate::types::create_type;
 use crate::vm::VirtualMachine;
 
 use adler32::RollingAdler32 as Adler32;
@@ -18,7 +19,11 @@ const DEF_BUF_SIZE: usize = 16 * 1024;
 pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
     let ctx = &vm.ctx;
 
-    let zlib_error = create_type("error", &ctx.type_type, &ctx.exceptions.exception_type);
+    let zlib_error = create_type(
+        "error",
+        &ctx.types.type_type,
+        &ctx.exceptions.exception_type,
+    );
 
     py_module!(vm, "zlib", {
         "crc32" => ctx.new_rustfunc(zlib_crc32),
diff --git a/vm/src/types.rs b/vm/src/types.rs
new file mode 100644
index 000000000..048b3d8ad
--- /dev/null
+++ b/vm/src/types.rs
@@ -0,0 +1,313 @@
+use crate::obj::objbool;
+use crate::obj::objbytearray;
+use crate::obj::objbytes;
+use crate::obj::objclassmethod;
+use crate::obj::objcode;
+use crate::obj::objcomplex;
+use crate::obj::objdict;
+use crate::obj::objellipsis;
+use crate::obj::objenumerate;
+use crate::obj::objfilter;
+use crate::obj::objfloat;
+use crate::obj::objframe;
+use crate::obj::objfunction;
+use crate::obj::objgenerator;
+use crate::obj::objint;
+use crate::obj::objiter;
+use crate::obj::objlist;
+use crate::obj::objmap;
+use crate::obj::objmappingproxy;
+use crate::obj::objmemory;
+use crate::obj::objmodule;
+use crate::obj::objnamespace;
+use crate::obj::objnone;
+use crate::obj::objobject;
+use crate::obj::objproperty;
+use crate::obj::objrange;
+use crate::obj::objset;
+use crate::obj::objslice;
+use crate::obj::objstaticmethod;
+use crate::obj::objstr;
+use crate::obj::objsuper;
+use crate::obj::objtuple;
+use crate::obj::objtype::{self, PyClass, PyClassRef};
+use crate::obj::objweakproxy;
+use crate::obj::objweakref;
+use crate::obj::objzip;
+use crate::pyobject::{PyAttributes, PyContext, PyObject, PyObjectRef};
+use std::cell::RefCell;
+use std::mem;
+use std::ptr;
+
+/// Holder of references to builtin types.
+#[derive(Debug)]
+pub struct TypeZoo {
+    pub bytes_type: PyClassRef,
+    pub bytesiterator_type: PyClassRef,
+    pub bytearray_type: PyClassRef,
+    pub bytearrayiterator_type: PyClassRef,
+    pub bool_type: PyClassRef,
+    pub classmethod_type: PyClassRef,
+    pub code_type: PyClassRef,
+    pub dict_type: PyClassRef,
+    pub enumerate_type: PyClassRef,
+    pub filter_type: PyClassRef,
+    pub float_type: PyClassRef,
+    pub frame_type: PyClassRef,
+    pub frozenset_type: PyClassRef,
+    pub generator_type: PyClassRef,
+    pub int_type: PyClassRef,
+    pub iter_type: PyClassRef,
+    pub complex_type: PyClassRef,
+    pub list_type: PyClassRef,
+    pub listiterator_type: PyClassRef,
+    pub listreverseiterator_type: PyClassRef,
+    pub striterator_type: PyClassRef,
+    pub strreverseiterator_type: PyClassRef,
+    pub dictkeyiterator_type: PyClassRef,
+    pub dictvalueiterator_type: PyClassRef,
+    pub dictitemiterator_type: PyClassRef,
+    pub dictkeys_type: PyClassRef,
+    pub dictvalues_type: PyClassRef,
+    pub dictitems_type: PyClassRef,
+    pub map_type: PyClassRef,
+    pub memoryview_type: PyClassRef,
+    pub tuple_type: PyClassRef,
+    pub tupleiterator_type: PyClassRef,
+    pub set_type: PyClassRef,
+    pub staticmethod_type: PyClassRef,
+    pub super_type: PyClassRef,
+    pub str_type: PyClassRef,
+    pub range_type: PyClassRef,
+    pub rangeiterator_type: PyClassRef,
+    pub slice_type: PyClassRef,
+    pub type_type: PyClassRef,
+    pub zip_type: PyClassRef,
+    pub function_type: PyClassRef,
+    pub builtin_function_or_method_type: PyClassRef,
+    pub property_type: PyClassRef,
+    pub readonly_property_type: PyClassRef,
+    pub module_type: PyClassRef,
+    pub namespace_type: PyClassRef,
+    pub bound_method_type: PyClassRef,
+    pub weakref_type: PyClassRef,
+    pub weakproxy_type: PyClassRef,
+    pub mappingproxy_type: PyClassRef,
+    pub object_type: PyClassRef,
+}
+
+impl Default for TypeZoo {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl TypeZoo {
+    pub fn new() -> Self {
+        let (type_type, object_type) = init_type_hierarchy();
+
+        let dict_type = create_type("dict", &type_type, &object_type);
+        let module_type = create_type("module", &type_type, &object_type);
+        let namespace_type = create_type("SimpleNamespace", &type_type, &object_type);
+        let classmethod_type = create_type("classmethod", &type_type, &object_type);
+        let staticmethod_type = create_type("staticmethod", &type_type, &object_type);
+        let function_type = create_type("function", &type_type, &object_type);
+        let builtin_function_or_method_type =
+            create_type("builtin_function_or_method", &type_type, &object_type);
+        let property_type = create_type("property", &type_type, &object_type);
+        let readonly_property_type = create_type("readonly_property", &type_type, &object_type);
+        let super_type = create_type("super", &type_type, &object_type);
+        let weakref_type = create_type("ref", &type_type, &object_type);
+        let weakproxy_type = create_type("weakproxy", &type_type, &object_type);
+        let generator_type = create_type("generator", &type_type, &object_type);
+        let bound_method_type = create_type("method", &type_type, &object_type);
+        let str_type = create_type("str", &type_type, &object_type);
+        let list_type = create_type("list", &type_type, &object_type);
+        let listiterator_type = create_type("list_iterator", &type_type, &object_type);
+        let listreverseiterator_type =
+            create_type("list_reverseiterator", &type_type, &object_type);
+        let striterator_type = create_type("str_iterator", &type_type, &object_type);
+        let strreverseiterator_type = create_type("str_reverseiterator", &type_type, &object_type);
+        let dictkeys_type = create_type("dict_keys", &type_type, &object_type);
+        let dictvalues_type = create_type("dict_values", &type_type, &object_type);
+        let dictitems_type = create_type("dict_items", &type_type, &object_type);
+        let dictkeyiterator_type = create_type("dict_keyiterator", &type_type, &object_type);
+        let dictvalueiterator_type = create_type("dict_valueiterator", &type_type, &object_type);
+        let dictitemiterator_type = create_type("dict_itemiterator", &type_type, &object_type);
+        let set_type = create_type("set", &type_type, &object_type);
+        let frozenset_type = create_type("frozenset", &type_type, &object_type);
+        let int_type = create_type("int", &type_type, &object_type);
+        let float_type = create_type("float", &type_type, &object_type);
+        let frame_type = create_type("frame", &type_type, &object_type);
+        let complex_type = create_type("complex", &type_type, &object_type);
+        let bytes_type = create_type("bytes", &type_type, &object_type);
+        let bytesiterator_type = create_type("bytes_iterator", &type_type, &object_type);
+        let bytearray_type = create_type("bytearray", &type_type, &object_type);
+        let bytearrayiterator_type = create_type("bytearray_iterator", &type_type, &object_type);
+        let tuple_type = create_type("tuple", &type_type, &object_type);
+        let tupleiterator_type = create_type("tuple_iterator", &type_type, &object_type);
+        let iter_type = create_type("iter", &type_type, &object_type);
+        let enumerate_type = create_type("enumerate", &type_type, &object_type);
+        let filter_type = create_type("filter", &type_type, &object_type);
+        let map_type = create_type("map", &type_type, &object_type);
+        let zip_type = create_type("zip", &type_type, &object_type);
+        let bool_type = create_type("bool", &type_type, &int_type);
+        let memoryview_type = create_type("memoryview", &type_type, &object_type);
+        let code_type = create_type("code", &type_type, &object_type);
+        let range_type = create_type("range", &type_type, &object_type);
+        let rangeiterator_type = create_type("range_iterator", &type_type, &object_type);
+        let slice_type = create_type("slice", &type_type, &object_type);
+        let mappingproxy_type = create_type("mappingproxy", &type_type, &object_type);
+
+        Self {
+            bool_type,
+            memoryview_type,
+            bytearray_type,
+            bytearrayiterator_type,
+            bytes_type,
+            bytesiterator_type,
+            code_type,
+            complex_type,
+            classmethod_type,
+            int_type,
+            float_type,
+            frame_type,
+            staticmethod_type,
+            list_type,
+            listiterator_type,
+            listreverseiterator_type,
+            striterator_type,
+            strreverseiterator_type,
+            dictkeys_type,
+            dictvalues_type,
+            dictitems_type,
+            dictkeyiterator_type,
+            dictvalueiterator_type,
+            dictitemiterator_type,
+            set_type,
+            frozenset_type,
+            tuple_type,
+            tupleiterator_type,
+            iter_type,
+            enumerate_type,
+            filter_type,
+            map_type,
+            zip_type,
+            dict_type,
+            str_type,
+            range_type,
+            rangeiterator_type,
+            slice_type,
+            object_type,
+            function_type,
+            builtin_function_or_method_type,
+            super_type,
+            mappingproxy_type,
+            property_type,
+            readonly_property_type,
+            generator_type,
+            module_type,
+            namespace_type,
+            bound_method_type,
+            weakref_type,
+            weakproxy_type,
+            type_type,
+        }
+    }
+}
+
+pub fn create_type(name: &str, type_type: &PyClassRef, base: &PyClassRef) -> PyClassRef {
+    let dict = PyAttributes::new();
+    objtype::new(type_type.clone(), name, vec![base.clone()], dict).unwrap()
+}
+
+fn init_type_hierarchy() -> (PyClassRef, PyClassRef) {
+    // `type` inherits from `object`
+    // and both `type` and `object are instances of `type`.
+    // to produce this circular dependency, we need an unsafe block.
+    // (and yes, this will never get dropped. TODO?)
+    let (type_type, object_type) = unsafe {
+        let object_type = PyObject {
+            typ: mem::uninitialized(), // !
+            dict: None,
+            payload: PyClass {
+                name: String::from("object"),
+                mro: vec![],
+                subclasses: RefCell::new(vec![]),
+                attributes: RefCell::new(PyAttributes::new()),
+            },
+        }
+        .into_ref();
+
+        let type_type = PyObject {
+            typ: mem::uninitialized(), // !
+            dict: None,
+            payload: PyClass {
+                name: String::from("type"),
+                mro: vec![object_type.clone().downcast().unwrap()],
+                subclasses: RefCell::new(vec![]),
+                attributes: RefCell::new(PyAttributes::new()),
+            },
+        }
+        .into_ref();
+
+        let object_type_ptr = PyObjectRef::into_raw(object_type.clone()) as *mut PyObject<PyClass>;
+        let type_type_ptr = PyObjectRef::into_raw(type_type.clone()) as *mut PyObject<PyClass>;
+
+        let type_type: PyClassRef = type_type.downcast().unwrap();
+        let object_type: PyClassRef = object_type.downcast().unwrap();
+
+        ptr::write(&mut (*object_type_ptr).typ, type_type.clone());
+        ptr::write(&mut (*type_type_ptr).typ, type_type.clone());
+
+        (type_type, object_type)
+    };
+
+    object_type
+        .subclasses
+        .borrow_mut()
+        .push(objweakref::PyWeak::downgrade(&type_type.as_object()));
+
+    (type_type, object_type)
+}
+
+/// Fill attributes of builtin types.
+pub fn initialize_types(context: &PyContext) {
+    objtype::init(&context);
+    objlist::init(&context);
+    objset::init(&context);
+    objtuple::init(&context);
+    objobject::init(&context);
+    objdict::init(&context);
+    objfunction::init(&context);
+    objstaticmethod::init(&context);
+    objclassmethod::init(&context);
+    objgenerator::init(&context);
+    objint::init(&context);
+    objfloat::init(&context);
+    objcomplex::init(&context);
+    objbytes::init(&context);
+    objbytearray::init(&context);
+    objproperty::init(&context);
+    objmemory::init(&context);
+    objstr::init(&context);
+    objrange::init(&context);
+    objslice::init(&context);
+    objsuper::init(&context);
+    objtuple::init(&context);
+    objiter::init(&context);
+    objellipsis::init(&context);
+    objenumerate::init(&context);
+    objfilter::init(&context);
+    objmap::init(&context);
+    objzip::init(&context);
+    objbool::init(&context);
+    objcode::init(&context);
+    objframe::init(&context);
+    objweakref::init(&context);
+    objweakproxy::init(&context);
+    objnone::init(&context);
+    objmodule::init(&context);
+    objnamespace::init(&context);
+    objmappingproxy::init(&context);
+}
diff --git a/vm/src/vm.rs b/vm/src/vm.rs
index da3348924..ce9382eaf 100644
--- a/vm/src/vm.rs
+++ b/vm/src/vm.rs
@@ -25,6 +25,7 @@ use crate::obj::objfunction::{PyFunction, PyMethod};
 use crate::obj::objgenerator::PyGenerator;
 use crate::obj::objint::PyInt;
 use crate::obj::objiter;
+use crate::obj::objmodule::{self, PyModule};
 use crate::obj::objsequence;
 use crate::obj::objstr::{PyString, PyStringRef};
 use crate::obj::objtuple::PyTupleRef;
@@ -32,8 +33,8 @@ use crate::obj::objtype;
 use crate::obj::objtype::PyClassRef;
 use crate::pyhash;
 use crate::pyobject::{
-    IdProtocol, ItemProtocol, PyContext, PyObjectRef, PyResult, PyValue, TryFromObject, TryIntoRef,
-    TypeProtocol,
+    IdProtocol, ItemProtocol, PyContext, PyObject, PyObjectRef, PyResult, PyValue, TryFromObject,
+    TryIntoRef, TypeProtocol,
 };
 use crate::scope::Scope;
 use crate::stdlib;
@@ -142,9 +143,23 @@ impl VirtualMachine {
         flame_guard!("init VirtualMachine");
         let ctx = PyContext::new();
 
+        // make a new module without access to the vm; doesn't
+        // set __spec__, __loader__, etc. attributes
+        let new_module = |name: &str, dict| {
+            PyObject::new(
+                PyModule {
+                    name: name.to_owned(),
+                },
+                ctx.types.module_type.clone(),
+                Some(dict),
+            )
+        };
+
         // Hard-core modules:
-        let builtins = ctx.new_module("builtins", ctx.new_dict());
-        let sysmod = ctx.new_module("sys", ctx.new_dict());
+        let builtins_dict = ctx.new_dict();
+        let builtins = new_module("builtins", builtins_dict.clone());
+        let sysmod_dict = ctx.new_dict();
+        let sysmod = new_module("sys", sysmod_dict.clone());
 
         let stdlib_inits = RefCell::new(stdlib::get_module_inits());
         let frozen = RefCell::new(frozen::get_module_inits());
@@ -168,6 +183,19 @@ impl VirtualMachine {
             signal_handlers: Default::default(),
         };
 
+        objmodule::init_module_dict(
+            &vm,
+            &builtins_dict,
+            vm.new_str("builtins".to_owned()),
+            vm.get_none(),
+        );
+        objmodule::init_module_dict(
+            &vm,
+            &sysmod_dict,
+            vm.new_str("sys".to_owned()),
+            vm.get_none(),
+        );
+
         builtins::make_module(&vm, builtins.clone());
         sysmodule::make_module(&vm, sysmod, builtins);
         vm
@@ -254,11 +282,22 @@ impl VirtualMachine {
         self.ctx.new_bool(b)
     }
 
+    pub fn new_module(&self, name: &str, dict: PyDictRef) -> PyObjectRef {
+        objmodule::init_module_dict(self, &dict, self.new_str(name.to_owned()), self.get_none());
+        PyObject::new(
+            PyModule {
+                name: name.to_owned(),
+            },
+            self.ctx.types.module_type.clone(),
+            Some(dict),
+        )
+    }
+
     #[cfg_attr(feature = "flame-it", flame("VirtualMachine"))]
     fn new_exception_obj(&self, exc_type: PyClassRef, args: Vec<PyObjectRef>) -> PyResult {
         // TODO: add repr of args into logging?
         vm_trace!("New exception created: {}", exc_type.name);
-        self.invoke(exc_type.into_object(), args)
+        self.invoke(&exc_type.into_object(), args)
     }
 
     pub fn new_empty_exception(&self, exc_type: PyClassRef) -> PyResult {
@@ -407,10 +446,23 @@ impl VirtualMachine {
     }
 
     pub fn import(&self, module: &str, from_list: &PyObjectRef, level: usize) -> PyResult {
-        let sys_modules = self.get_attribute(self.sys_module.clone(), "modules")?;
-        sys_modules
-            .get_item(module.to_string(), self)
-            .or_else(|_| {
+        // if the import inputs seem weird, e.g a package import or something, rather than just
+        // a straight `import ident`
+        let weird = module.contains('.')
+            || level != 0
+            || objbool::boolval(self, from_list.clone()).unwrap_or(true);
+
+        let module = self.new_str(module.to_owned());
+
+        let cached_module = if weird {
+            None
+        } else {
+            let sys_modules = self.get_attribute(self.sys_module.clone(), "modules")?;
+            sys_modules.get_item(module.clone(), self).ok()
+        };
+        match cached_module {
+            Some(module) => Ok(module),
+            None => {
                 let import_func = self
                     .get_attribute(self.builtins.clone(), "__import__")
                     .map_err(|_| self.new_import_error("__import__ not found".to_string()))?;
@@ -424,17 +476,18 @@ impl VirtualMachine {
                     (self.get_none(), self.get_none())
                 };
                 self.invoke(
-                    import_func,
+                    &import_func,
                     vec![
-                        self.ctx.new_str(module.to_string()),
+                        module,
                         globals,
                         locals,
                         from_list.clone(),
                         self.ctx.new_int(level),
                     ],
                 )
-            })
-            .map_err(|exc| import::remove_importlib_frames(self, &exc))
+                .map_err(|exc| import::remove_importlib_frames(self, &exc))
+            }
+        }
     }
 
     /// Determines if `obj` is an instance of `cls`, either directly, indirectly or virtually via
@@ -463,7 +516,7 @@ impl VirtualMachine {
 
     pub fn call_get_descriptor(&self, attr: PyObjectRef, obj: PyObjectRef) -> PyResult {
         let attr_class = attr.class();
-        if let Some(descriptor) = objtype::class_get_attr(&attr_class, "__get__") {
+        if let Some(ref descriptor) = objtype::class_get_attr(&attr_class, "__get__") {
             let cls = obj.class();
             self.invoke(descriptor, vec![attr, obj.clone(), cls.into_object()])
         } else {
@@ -487,14 +540,14 @@ impl VirtualMachine {
                     func
                 );
                 let wrapped = self.call_get_descriptor(func, obj.clone())?;
-                self.invoke(wrapped, args)
+                self.invoke(&wrapped, args)
             }
             None => Err(self.new_type_error(format!("Unsupported method: {}", method_name))),
         }
     }
 
     #[cfg_attr(feature = "flame-it", flame("VirtualMachine"))]
-    fn _invoke(&self, func_ref: PyObjectRef, args: PyFuncArgs) -> PyResult {
+    fn _invoke(&self, func_ref: &PyObjectRef, args: PyFuncArgs) -> PyResult {
         vm_trace!("Invoke: {:?} {:?}", func_ref, args);
 
         if let Some(PyFunction {
@@ -513,7 +566,7 @@ impl VirtualMachine {
             ref object,
         }) = func_ref.payload()
         {
-            self.invoke(function.clone(), args.insert(object.clone()))
+            self.invoke(&function, args.insert(object.clone()))
         } else if let Some(PyBuiltinFunction { ref value }) = func_ref.payload() {
             value(self, args)
         } else {
@@ -523,9 +576,8 @@ impl VirtualMachine {
         }
     }
 
-    // TODO: make func_ref an &PyObjectRef
     #[inline]
-    pub fn invoke<T>(&self, func_ref: PyObjectRef, args: T) -> PyResult
+    pub fn invoke<T>(&self, func_ref: &PyObjectRef, args: T) -> PyResult
     where
         T: Into<PyFuncArgs>,
     {
@@ -546,7 +598,7 @@ impl VirtualMachine {
             let trace_func = self.trace_func.borrow().clone();
             if !self.is_none(&trace_func) {
                 self.use_tracing.replace(false);
-                let res = self.invoke(trace_func, args.clone());
+                let res = self.invoke(&trace_func, args.clone());
                 self.use_tracing.replace(true);
                 res?;
             }
@@ -554,7 +606,7 @@ impl VirtualMachine {
             let profile_func = self.profile_func.borrow().clone();
             if !self.is_none(&profile_func) {
                 self.use_tracing.replace(false);
-                let res = self.invoke(profile_func, args);
+                let res = self.invoke(&profile_func, args);
                 self.use_tracing.replace(true);
                 res?;
             }
@@ -592,7 +644,7 @@ impl VirtualMachine {
 
     pub fn invoke_with_locals(
         &self,
-        function: PyObjectRef,
+        function: &PyObjectRef,
         cells: PyDictRef,
         locals: PyDictRef,
     ) -> PyResult {
@@ -605,7 +657,7 @@ impl VirtualMachine {
         }
         panic!(
             "invoke_with_locals: expected python function, got: {:?}",
-            function
+            *function
         );
     }
 
@@ -831,7 +883,7 @@ impl VirtualMachine {
     {
         if let Some(method_or_err) = self.get_method(obj.clone(), method) {
             let method = method_or_err?;
-            let result = self.invoke(method, vec![arg.clone()])?;
+            let result = self.invoke(&method, vec![arg.clone()])?;
             if !result.is(&self.ctx.not_implemented()) {
                 return Ok(result);
             }
@@ -864,6 +916,43 @@ impl VirtualMachine {
         })
     }
 
+    pub fn generic_getattribute(
+        &self,
+        obj: PyObjectRef,
+        name_str: PyStringRef,
+    ) -> PyResult<Option<PyObjectRef>> {
+        let name = name_str.as_str();
+        let cls = obj.class();
+
+        if let Some(attr) = objtype::class_get_attr(&cls, &name) {
+            let attr_class = attr.class();
+            if objtype::class_has_attr(&attr_class, "__set__") {
+                if let Some(descriptor) = objtype::class_get_attr(&attr_class, "__get__") {
+                    return self
+                        .invoke(&descriptor, vec![attr, obj, cls.into_object()])
+                        .map(Some);
+                }
+            }
+        }
+
+        let attr = if let Some(ref dict) = obj.dict {
+            dict.get_item_option(name_str.clone(), self)?
+        } else {
+            None
+        };
+
+        if let Some(obj_attr) = attr {
+            Ok(Some(obj_attr))
+        } else if let Some(attr) = objtype::class_get_attr(&cls, &name) {
+            self.call_get_descriptor(attr, obj).map(Some)
+        } else if let Some(getter) = objtype::class_get_attr(&cls, "__getattr__") {
+            self.invoke(&getter, vec![obj, name_str.into_object()])
+                .map(Some)
+        } else {
+            Ok(None)
+        }
+    }
+
     pub fn is_callable(&self, obj: &PyObjectRef) -> bool {
         match_class!(obj,
             PyFunction => true,
@@ -1132,7 +1221,7 @@ impl VirtualMachine {
     pub fn _membership(&self, haystack: PyObjectRef, needle: PyObjectRef) -> PyResult {
         if let Some(method_or_err) = self.get_method(haystack.clone(), "__contains__") {
             let method = method_or_err?;
-            self.invoke(method, vec![needle])
+            self.invoke(&method, vec![needle])
         } else {
             self._membership_iter_search(haystack, needle)
         }
diff --git a/wasm/lib/src/browser_module.rs b/wasm/lib/src/browser_module.rs
index fed4fcbdc..abfdc2b53 100644
--- a/wasm/lib/src/browser_module.rs
+++ b/wasm/lib/src/browser_module.rs
@@ -133,7 +133,7 @@ fn browser_request_animation_frame(func: PyCallable, vm: &VirtualMachine) -> PyR
         let vm = &stored_vm.vm;
         let func = func.clone();
         let args = vec![vm.ctx.new_float(time)];
-        let _ = vm.invoke(func.into_object(), args);
+        let _ = vm.invoke(&func.into_object(), args);
 
         let closure = f.borrow_mut().take();
         drop(closure);
@@ -212,12 +212,12 @@ impl PyPromise {
                     } else {
                         vec![convert::js_to_py(vm, val)]
                     };
-                    vm.invoke(on_fulfill.into_object(), PyFuncArgs::new(args, vec![]))
+                    vm.invoke(&on_fulfill.into_object(), PyFuncArgs::new(args, vec![]))
                 }
                 Err(err) => {
                     if let OptionalArg::Present(on_reject) = on_reject {
                         let err = convert::js_to_py(vm, err);
-                        vm.invoke(on_reject.into_object(), PyFuncArgs::new(vec![err], vec![]))
+                        vm.invoke(&on_reject.into_object(), PyFuncArgs::new(vec![err], vec![]))
                     } else {
                         return Err(err);
                     }
@@ -240,7 +240,7 @@ impl PyPromise {
                     .expect("that the vm is valid when the promise resolves");
                 let vm = &stored_vm.vm;
                 let err = convert::js_to_py(vm, err);
-                let res = vm.invoke(on_reject.into_object(), PyFuncArgs::new(vec![err], vec![]));
+                let res = vm.invoke(&on_reject.into_object(), PyFuncArgs::new(vec![err], vec![]));
                 convert::pyresult_to_jsresult(vm, res)
             })
         });
diff --git a/wasm/lib/src/convert.rs b/wasm/lib/src/convert.rs
index f4c71e60d..16b7fe3f7 100644
--- a/wasm/lib/src/convert.rs
+++ b/wasm/lib/src/convert.rs
@@ -94,7 +94,7 @@ pub fn py_to_js(vm: &VirtualMachine, py_obj: PyObjectRef) -> JsValue {
                                 .insert(js_sys::JsString::from(key).into(), js_to_py(vm, val));
                         }
                     }
-                    let result = vm.invoke(py_obj.clone(), py_func_args);
+                    let result = vm.invoke(&py_obj, py_func_args);
                     pyresult_to_jsresult(vm, result)
                 };
             let closure = Closure::wrap(Box::new(closure)
diff --git a/wasm/lib/src/js_module.rs b/wasm/lib/src/js_module.rs
index 9468aa416..9622613f7 100644
--- a/wasm/lib/src/js_module.rs
+++ b/wasm/lib/src/js_module.rs
@@ -1,9 +1,8 @@
 use js_sys::{Array, Object, Reflect};
 use rustpython_vm::function::Args;
 use rustpython_vm::obj::{objfloat::PyFloatRef, objstr::PyStringRef, objtype::PyClassRef};
-use rustpython_vm::pyobject::{
-    create_type, PyClassImpl, PyObjectRef, PyRef, PyResult, PyValue, TryFromObject,
-};
+use rustpython_vm::pyobject::{PyClassImpl, PyObjectRef, PyRef, PyResult, PyValue, TryFromObject};
+use rustpython_vm::types::create_type;
 use rustpython_vm::VirtualMachine;
 use wasm_bindgen::{prelude::*, JsCast};
 
@@ -244,7 +243,7 @@ fn new_js_error(vm: &VirtualMachine, err: JsValue) -> PyObjectRef {
 pub fn make_module(vm: &VirtualMachine) -> PyObjectRef {
     let ctx = &vm.ctx;
     py_module!(vm, "_js", {
-        "JsError" => create_type("JsError", &ctx.type_type, &ctx.exceptions.exception_type),
+        "JsError" => create_type("JsError", &ctx.type_type(), &ctx.exceptions.exception_type),
         "JsValue" => PyJsValue::make_class(ctx),
     })
 }
diff --git a/wasm/lib/src/vm_class.rs b/wasm/lib/src/vm_class.rs
index 5015c3925..1f2584f0a 100644
--- a/wasm/lib/src/vm_class.rs
+++ b/wasm/lib/src/vm_class.rs
@@ -256,7 +256,7 @@ impl WASMVirtualMachine {
             let mod_name = name.clone();
 
             let stdlib_init_fn = move |vm: &VirtualMachine| {
-                let module = vm.ctx.new_module(&name, vm.ctx.new_dict());
+                let module = vm.new_module(&name, vm.ctx.new_dict());
                 for (key, value) in module_items.clone() {
                     vm.set_attr(&module, key, value).unwrap();
                 }