PEP 3119 – Introducing Abstract Base Classes
https://peps.python.org/pep-3119/
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）なぜこれが Python に付け加えられたか（Python abcより）
👉Python用語集 抽象基底クラス（特殊メソッドはhasattrでは微妙に誤るとのこと）
（積ん読）ABCs for Containers and Iterators