PROGRAM

  ROUTINE trace
  BEGIN
    FORWARD 70 ;
    ROTATE 60 ;
  END

BEGIN
  FORWARD 100 ;
  ROTATE 90;
  FORWARD 100;
  ROTATE 270;
  PEN DOWN;
  CALL trace;
  CALL trace;
  CALL trace;
  CALL trace;
  CALL trace;
  CALL trace;
END.