Utility classes for dealing with circular references.
| Class | NotKnown | Undocumented |
| Class | _Container | Helper class to resolve circular references on container objects. |
| Class | _Tuple | Manage tuple containing circular references. Deprecated: use _Container instead. |
| Class | _InstanceMethod | Undocumented |
| Class | _DictKeyAndValue | Undocumented |
| Class | _Dereference | Undocumented |
| Class | _Defer | Undocumented |