gistfile1.txt

    In [11]: class Abc:
        ...:     def __init_subclass__(cls):
        ...:         print(cls)
        ...:         

    In [12]: class C(Abc):
        ...:     pass
        ...: 

    In [13]: C()
    Out[13]: <__main__.C at 0x7fcb8b44e630>

    In [14]: C()
    Out[14]: <__main__.C at 0x7fcb8b44e9e8>