anchor.diff:  
     Color _color;
     Color get color => _color;
  -  void set color (Color value) {
  -    assert(value != null);
  -    if (_color == value)
  -      return;
  -    _color = value;
  +  void set color (Color newColor) {
  +    assert(newColor != null);
  +    if (_color == newColor)
  +      return;
  +    _color = newColor;
       markNeedsPaint();
     }
   
     sky.TransferMode _transferMode;
     sky.TransferMode get transferMode => _transferMode;
  -  void set transferMode (sky.TransferMode value) {
  -    assert(value != null);
  -    if (_transferMode == value)
  -      return;
  -    _transferMode = value;
  +  void set transferMode (sky.TransferMode newTransferMode) {
  +    assert(newTransferMode != null);
  +    if (_transferMode == newTransferMode)
  +      return;
  +    _transferMode = newTransferMode;
       markNeedsPaint();
     }
   
  
positive.code:   final BoxPainter _painter;
  
    BoxDecoration get decoration => _painter.decoration;
    void set decoration (BoxDecoration value) {
      assert(value != null);
      if (value == _painter.decoration)
        return;
      _removeBackgroundImageListenerIfNeeded();
      _painter.decoration = value;
      _addBackgroundImageListenerIfNeeded();
      markNeedsPaint();
    }
  
negative.code: 
    double _aspectRatio;
    double get aspectRatio => _aspectRatio;
    void set aspectRatio (double newAspectRatio) {
      assert(newAspectRatio != null);
      if (_aspectRatio == newAspectRatio)
        return;
      _aspectRatio = newAspectRatio;
      markNeedsLayout();
    }
  
  