import abc

#class Base1(metaclass=abc.ABCMeta):
class Base1():
    class_variable_one = 0

    @abc.abstractmethod
    def test_func(self):
        pass


class Derived1(Base1):
    def __init__(self):
        print(Base1.class_variable_one)
        self.class_variable_one = 1

    def get_base(self):
        return Base1

class Derived2(Base1):
    def __init__(self):
        print(Base1.class_variable_one)
        self.class_variable_one = 2

if __name__ == '__main__':
    base1 = Base1()
    print(base1.class_variable_one)
    derived1 = Derived1()
    print(derived1.class_variable_one)
    derived2 = Derived2()
    print(derived2.class_variable_one)


    print(base1.class_variable_one)
    print(derived1.class_variable_one)
    print(derived2.class_variable_one)

    print('\n')

    print(derived1.get_base().class_variable_one)
    print(derived1.class_variable_one)