void testMove(Point p) {
  p.move(10, 10);
  p.print();
}

void main() {
  Point p = new Point(1, 2);
  ColorPoint cp = new ColorPoint(3, 4, "green");
  DeepPoint dp = new DeepPoint(5, 6, 5);

  testMove(p);
  testMove(cp);
  testMove(dp);
}