anchor.diff:      Offset to,
       List<Color> colors, [
       List<double> colorStops = null,
  -    TileMode tileMode = TileMode.clamp
  +    TileMode tileMode = TileMode.clamp,
     ]) {
       _validateColorStops(colors, colorStops);
       final Float32List endPointsBuffer = _encodeTwoPoints(from, to);
  
positive.code:   /// `color` must therefore only have two entries).
    ///
    /// The behavior before `from` and after `to` is described by the `tileMode`
    /// argument.
    ///
    /// If `from`, `to`, `colors`, or `tileMode` are null, or if `colors` or
    /// `colorStops` contain null values, this constructor will throw a
  
negative.code:   /// `color` must therefore only have two entries).
    ///
    /// The behavior before and after the radius is described by the `tileMode`
    /// argument. For details, see the [TileMode] enum.
    ///
    /// ![](https://flutter.github.io/assets-for-api-docs/dart-ui/tile_mode_clamp_radial.png)
    /// ![](https://flutter.github.io/assets-for-api-docs/dart-ui/tile_mode_mirror_radial.png)
    /// ![](https://flutter.github.io/assets-for-api-docs/dart-ui/tile_mode_repeated_radial.png)
    ///
    /// If `center`, `radius`, `colors`, or `tileMode` are null, or if `colors` or
    /// `colorStops` contain null values, this constructor will throw a
    /// [NoSuchMethodError].
    Gradient.radial(Offset center,
                    double radius,
                    List<Color> colors, [
                    List<double> colorStops = null,
                    TileMode tileMode = TileMode.clamp,
    ]) {
      _validateColorStops(colors, colorStops);
      final Int32List colorsBuffer = _encodeColorList(colors);
      final Float32List colorStopsBuffer = colorStops == null ? null : new Float32List.fromList(colorStops);
  