p1 = Point(20, 30)
    p1.move_to(111, 222)
    p1.move_by(10, 20)
    p1.move_to(0, 0)
    p1.move_to(21, 31)
    print('p1 from start to (21, 31), should be about 1.414',
          p1.distance_from_start())

    p1.move_by(29, 39)
    print('p1 from start to (50, 70), should be about 50.0',
          p1.distance_from_start())

    p2 = Point(1, 1)
    print('p2 from start to (1, 1), should be about 0.0',
          p2.distance_from_start())

    p2.move_to(11, 1)
    print('p2 from start to (11, 1), should be about 10.0',
          p2.distance_from_start())

    p2.move_to(999, 999)
    p2.move_to(1, 1)
    print('p2 from start to (1, 1), should be about 0.0',
          p2.distance_from_start())