Rectangle

class Point:
    def __init__(self, x=0, y=0):
        self.x = x
        self.y = y


a = Point(1, 4)
b = Point(4, 4)
c = Point(1, 2)
d = Point(4, 2)


class Rectangle:
    def __init__(self, a, b, c, d):
        self.a = a
        self.b = b
        self.c = c
        self.d = d

    def area(self):
        hei = a.y - c.y
        len = b.x - a.x
        return len * hei


r = Rectangle(a, b, c, d)


print r.area()
a.x = 10
print r.area()