Um, that patch contains only the C code for overloading isinstance() and issubclass(). Did you do anything about abc.py and _abcoll.py/collections.py and their respective unit tests? Or what about the unit tests for isinstance()/issubclass()? On 8/25/07, Benjamin Aranguren <baranguren at gmail.com> wrote: > Worked with Alex Martelli at the Goolge Python Sprint. -- --Guido van Rossum (home page: http://www.python.org/~guido/)