mammals

mammals.py

class Dog(Mammal):
    pass

class Cat(Mammal):
    pass

TMammal = TypeVar("TMammal", bound=Mammal)

class MammalCollection(Generic[TMammal]):
    def __init__(self, *mammals: TMammal) -> None:
        self.__mammals = [*mammals]

    def add(self, mammal: TMammal) -> None:
        self.__mammals.append(mammal)


if __name__ == '__main__':
    collection = MammalCollection(Dog())
    collection.add(Cat())  # This won't work now because it is a mammal collection of Dog()