anchor.diff:     */
     slowDown() {
       if (_speedUnderEqualMinSpeed() && _accelerationDirection == -1) {
  -      _accelerationDirection = 0;
  +      _accelerationDirection = _NO_ACCELERATION_DIRECTION;
       } else {
  -      _accelerationDirection = -1;
  +      _accelerationDirection = _SLOW_DOWN_DIRECTION;
       }
     }
   
  
positive.code:    */
    speedUP() {
      if (_speedOverEqualMaxSpeed() && _accelerationDirection == 1) {
        _accelerationDirection = 0;
      } else {
        _accelerationDirection = 1;
      }
    }
  
  
negative.code:   final StageXL.Vector _zeroOneVector = new StageXL.Vector(0, 1);
  
    final StageXL.Vector _oneZeroVector = new StageXL.Vector(1, 0);
    
    static const int _NO_ACCELERATION_DIRECTION = 0;
    
    static const int _SPEED_UP_DIRECTION = 1;
    
    static const int _SLOW_DOWN_DIRECTION = -1;
    
    static const int _MAX_LENGTH_FOR_MAIN_DIRECTION = 1;
    
    static const double _MAX_LENGTH_WITH_PRECISION = 1.001;
  
    /**
     * Does the sprite move?
  