anchor.diff:      this._model = model;
       this._parts = parts;
       this._hitpoints = hitpoints;
  +    this._baseHitpoints = hitpoints;
       setup();
       print('Spawned ship on $this');
     }
  
positive.code: 
      if (this._hitpoints <= 0) {
        this._model.removeEnemy(this);
        this._model.addScore(this._hitpoints);
        print('Ship is destroyed!');
      }
    }
  
negative.code:   Map<String, int> _leftMost;
    Map<String, int> _rightMost;
  
    int _baseHitpoints;
    int _hitpoints;
  
    /**
  