PEP 3119 – Introducing Abstract Base Classes
proposes
A way to overload isinstance() and issubclass()
A new module abc which serves as an “ABC support framework”.
It defines a metaclass for use with ABCs and a decorator that can be used to define abstract methods.
Specific ABCs for containers and iterators, to be added to the collections module.
(積ん読)ABCs for Containers and Iterators