public AttackingState(
     World world, 
     Body body, 
     ComputerControlledTank tank)
 {
     this.world = world;
     this.body = body;
     this.tank = tank;
 }
 public TurningState(Body body, ComputerControlledTank tank)
 {
     this.body = body;
     this.tank = tank;
 }