anchor.diff:    /**
      * Überprüfen ob der Tetris Stein am Grund angekommen ist
      */
  -  bool onGround(var moveTo) {
  +  bool notOnGround(var moveTo) {
       bool stoneOne = moveTo.elementAt(0)['row'] >= 0&&
           moveTo.elementAt(0)['row'] < _game._sizeHeight;
   
  
positive.code:       { 'row' : _stone.elementAt(3)['row'] + _dr,  'col' : _stone.elementAt(3)['col'] + _dc  }
      ];
  
  /*<<<<<<< HEAD
    /*TODO: check if the tetromino can be moved. It could be blocked by the
      bottom of the field or another tetromino that's already placed.*/
      if (onField(_move) && !_isMoveBlocked(_move)){
        this._stone.forEach((piece){
          this._game._field[piece['row']][piece['col']].isActive = false;
          this._game._field[piece['row']][piece['col']].color = #empty;
        });
        _stone = _move;
      } else {
        nextTetris();
  =======*/
      // Prüfen ob der Tetris Stein die Seiten verlässt
      if (onSide(_move)){
        // Prüfen ob der Stein den Grund des Feldes erreicht
        if (onGround(_move)){
          this._stone.forEach((piece){
            this._game._field[piece['row']][piece['col']].isActive = false;
            this._game._field[piece['row']][piece['col']].color = #empty;
          });
          _stone = _move;
        } else {
          nextTetris();
        }
  
negative.code:     this._game.updateField();
    }
  
    /**
     * Teilt dem Tetris Stein die Bewegung nach unten mit [move]s.
     */
  