anchor.diff:      this.tileMode: sky.TileMode.clamp
     });
   
  -  String toString() =>
  -      'RadialGradient($center, $radius, $colors, $colorStops, $tileMode)';
  -
  -  sky.Shader createShader() {
  -    return new sky.Gradient.radial(this.center, this.radius, this.colors,
  -                                   this.colorStops, this.tileMode);
  -  }
  -
     final Point center;
     final double radius;
     final List<Color> colors;
     final List<double> colorStops;
     final sky.TileMode tileMode;
  +
  +  sky.Shader createShader() {
  +    return new sky.Gradient.radial(this.center, this.radius, this.colors,
  +                                   this.colorStops, this.tileMode);
  +  }
  +
  +  String toString() {
  +    return 'RadialGradient($center, $radius, $colors, $colorStops, $tileMode)';
  +  }
   }
   
   enum BackgroundFit { fill, contain, cover, none, scaleDown }
  
positive.code:   if (b == null)
      return a.scale(1.0 - t);
    return new BoxShadow(
        color: lerpColor(a.color, b.color, t),
        offset: lerpOffset(a.offset, b.offset, t),
        blur: lerpNum(a.blur, b.blur, t));
  }
  
  List<BoxShadow> lerpListBoxShadow(List<BoxShadow> a, List<BoxShadow> b, double t) {
  
negative.code:     this.tileMode: sky.TileMode.clamp
    });
  
    final List<Point> endPoints;
    final List<Color> colors;
    final List<double> colorStops;
    final sky.TileMode tileMode;
  
    sky.Shader createShader() {
      return new sky.Gradient.linear(this.endPoints, this.colors,
                                     this.colorStops, this.tileMode);
    }
  
    String toString() {
      return 'LinearGradient($endPoints, $colors, $colorStops, $tileMode)';
    }
  }
  
  class RadialGradient extends Gradient {
  