The example object in the xxlimited module can be part of a reference loop (it can contain itself), so it needs GC and tp_traverse.

The tp_dealloc hook was incorrect, and a correct version would be difficult to generalize for something more complicated than a example class (#16690; [0]). It's better to avoid dealloc and show off tp_finalize.

Same for the class in _testmultiphase (PEP 489 tests), which is based on xxlimited. The incorrect dealloc is causing the reference leak mentioned in #24268.

The Xxo object also wasn't actually added to the module.

Here is a patch to fix these.

[0] https://mail.python.org/pipermail/python-dev/2015-June/140422.html