Replace vm.obj_len to obj.length

vm/src/protocol/object.rs

@@ -151,7 +151,12 @@ impl PyObjectRef {
     // int PyObject_TypeCheck(PyObject *o, PyTypeObject *type)
 
     pub fn length(&self, vm: &VirtualMachine) -> PyResult<usize> {
-        vm.obj_len(self)
+        vm.obj_len_opt(self).unwrap_or_else(|| {
+            Err(vm.new_type_error(format!(
+                "object of type '{}' has no len()",
+                self.class().name()
+            )))
+        })
     }
 
     pub fn length_hint(

vm/src/vm.rs

@@ -1920,15 +1920,6 @@ impl VirtualMachine {
             })
     }
 
-    pub fn obj_len(&self, obj: &PyObjectRef) -> PyResult<usize> {
-        self.obj_len_opt(obj).unwrap_or_else(|| {
-            Err(self.new_type_error(format!(
-                "object of type '{}' has no len()",
-                obj.class().name()
-            )))
-        })
-    }
-
     pub fn length_hint(&self, iter: PyObjectRef) -> PyResult<Option<usize>> {
         if let Some(len) = self.obj_len_opt(&iter) {
             match len {