poly.py

class Private:
    __number = 1
    # def __add__(self, other):
        
    def __say(self):
        print('private say')
    def say(self):
        print('public say')
        self.__say()
    def _say(self):
        print('protected say')


class Car:
    VAN = 'van'
    COUPE = 'coupe'
    RACE = 'race'
    @property
    def __subtypes
        return {
            VAN: Van,
            COUPE: Coupe,
            RACE: Race
        }
    @classmethod
    def factory(cls, sub_type, *args, **kwargs):
        sub_car = self.__subtypes[sub_type]
        if isinstance(sub_car, cls): 
            return self.__subtypes[sub_type](*args, **kwargs)

        raise AssertionError

    def drive(self):
        raise NotImplementedError

class Van(Car):
    pass
class Coupe(Car):
    pass

class Race(Car):
    pass

coupe = Car.factory(Car.COUPE)
van = Car.factory(Car.VAN)

class Number:
    def __init__(self, n):
        self.n = n
    def __str__(self):
        return str(self.n)
    def __eq__(self, other):
        return self.n == other.n
    def __add__(self, other):
        return self.__class__(self.n + other.n)
    

n1 = Number(1)
n2 = Number(1)


print(n1 == n2)