p1 = Point(30, 18)
    print('p1: Should print 30, 18:', p1.x, p1.y)

    p2 = Point(100, -40)
    print('p1: Should still print 30, 18:', p1.x, p1.y)
    print('p2: Should print 100, -40:', p2.x, p2.y)

    p1.y = 500
    print('p1: Should now print 30, 500:', p1.x, p1.y)
    print('p2: Should still print 100, -40:', p2.x, p2.y)