anchor.diff:        _lastTimestamp = delta;
         clear();
         drawCell(_food, "blue");
  -      _snake.update(ctx, _keyboard);
  +      _snake.update();
         _checkForCollisions();
       }
   
  
positive.code:   num _lastTimestamp = 0;
    int _rightEdgeX;
    int _bottomEdgeY;
  
    Keyboard _keyboard = new Keyboard();
  
    Snake _snake;
    Point _food;
  
negative.code:   }
  
    bool isPressed(int keyCode) => _keys.containsKey(keyCode);
  }