Listing 4
  public class LineMaker
                    extends ShapeMaker
  {
    public LineMaker(int street, 
                     int avenue,
                     Direction facing,
                     int beepers)
    {
      super(street, avenue,
            facing, beepers);
    }

    public void makeShape()
    {
      move();
      putBeeper();
      move();
      putBeeper();
      move();
      putBeeper();
      move();
      turnOff();
    }
  }