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

    def __eq__(self, other):
        return self.x == other.x and self.y == other.y

    def __str__(self):
        return '({0.x}, {0.y})'.format(self)

    def func(self):
        return abs(self.x-self.y)


a = Point()
print(str(a))
b = Point(3,4)
print(str(b))
b.x = -19
print(a.func())
print(str(b))
print(a == b, a != b)

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

    def area(self):
        return math.pi*2*