class Pipe:
    state = True
    def draw(self):
        print("I am a pipe.")
        if(self.state):
            print("I am enabled.")
        else:
            print("I am disabled.")


class FastPipe(Pipe):
    speed = 1.0
    def draw(self):
        Pipe.draw(self)
        print("I transport things quickly.")
        print("My speed is", self.speed)


pipe = Pipe()
pipe.state = False
pipe.draw()
print("")
pipe.__class__ = FastPipe
pipe.speed += 0.5
pipe.draw()