Simple snippet of Python Inheritance

Inheritance.py

class Shape(object) :

    def __init__(self) :
        self.dummyVar = 9

    def area(self) :
        raise NotImplementedError("You must implement area method in the {0} sub class.".format(self.__class__.__name__))

    def perimeter(self) :
        raise NotImplementedError("You must implement area method in the {0} sub class".format(self.__class__.__name__))

    def randomJunk(self) :
        print("Random Junk!")

class Rectangle(Shape) :

    def __init__(self, length, width) :
        self.length = length
        self.width = width
        super().__init__()

    def area(self) :
        return self.length * self.width

    def perimeter(self) :
        return self.length * 2 + self.width * 2

class Square(Rectangle) :
    def __init__(self, side) :
        self.side = side
        super().__init__(side, side)

def main() :
    rectangle = Rectangle(5, 8)
    square = Square(6)

    # Method calls through one level of inheritance
    print(rectangle.area())
    print(rectangle.perimeter())
    rectangle.randomJunk()

    # Method calls through one level of inheritance
    print(square.area())
    print(square.length)
    
    # Call through two levels of inheritance
    print(square.dummyVar)

if __name__ == "__main__":
    main()