'''
Define a class named Shape and its subclass Square.
The Square class has an init function which takes a length as argument.
Both classes have a area function which can print the area of the shape where Shape's area is 0 by default.
 
'''

class Shape:

    def __init__(self):
        pass
    def area(self):
        return 0

class Square(Shape):

    def __init__(self,l):
        Shape.__init__(self)
        self.length = l

    def area(self):
        return self.length**2


a = Shape()
print(a.area())
