anchor.diff:    int score;
     Text scoreText;
   
  -  Ship player;
  +  Sprite player;
     Group<Sprite> bullets;
     Group<Ufo> ufos;
   
  
positive.code:       scoreText.text = "Score: ${score+=10}";
      });
  
      game.physics.collison(ufos, player, (Ufo ufo, Ship player) {
        bulletTimer.cancel();
        killState();
      });
  
negative.code:     score = 0;
      scoreText = game.add.text("Score: $score", size: 20);
  
      player = game.add.sprite('playerShip1_blue')
          ..x = game.world.width ~/ 2
          ..y = game.world.height - 200;
  
      bullets = new Group<Sprite>();
      for (int i = 0; i < 5; i++) {
  