'''
Extending from ABC makes
this class abstract
'''

from abc import ABC, abstractmethod

class A(ABC):
    def __init__(self):
        self.a = 40
    # Abstract methods have to be annotated
    @abstractmethod
    def some_method(self):
    # abstract methods can, but usually
    # don't have an implementation
        pass


class B(A):
    def __init__(self):
        super().__init__()
        self.b = 50

    # Class B now has to implement
    # some_method
    def some_method(self):
        print('some_method in B')

objekt = B()