Listing 1
import kareltherobot.*;

// ShapeMaker adds some extra 
// moves to your basic Robot
public abstract class ShapeMaker
                  extends Robot
{

  public ShapeMaker(int street, 
                    int avenue,
                    Direction facing,
                    int beepers)
  {
    super(street, avenue, 
            facing, beepers);
  }

  // To turn right, turn
  // left three times
  public void turnRight()
  {
    turnLeft();
    turnLeft();
    turnLeft();
  }
  
  // To turn around,
  // turn left twice
  public void turnAround()
  {
    turnLeft();
    turnLeft();
  }

  // Move one space forward
  // and one to the right
  public void diagonalRight()
  {
    move();
    turnRight();
    move();
    turnLeft();
  }
  
  // Move one space forward
  // and one to the left
  public void diagonalLeft()
  {
    move();
    turnLeft();
    move();
    turnRight();
  }

  // Every ShapeMaker type robot
  // must define a makeShape() method
  public abstract void makeShape();
}