shape.py

class Shape:
    
    def area(self):
        pass
    
    def perimeter(self):
        pass
    
    
class Square(Shape):
    
    def __init__(self, side):
        self.side = side
        
    def area(self):
        return self.side ** 2

    
shape_obj = Shape()
square_obj = Square(5)

print(square_obj.area())