anchor.diff:    final List<double> gradientColorStops;
   
     BetweenBarsData({
  -    @required this.fromIndex,
  -    @required this.toIndex,
  -    this.colors = const [Colors.blueGrey],
  -    this.gradientFrom = const Offset(0, 0),
  -    this.gradientTo = const Offset(1, 0),
  -    this.gradientColorStops,
  -  });
  +    @required int fromIndex,
  +    @required int toIndex,
  +    List<Color> colors,
  +    Offset gradientFrom,
  +    Offset gradientTo,
  +    List<double> gradientColorStops,
  +  })
  +    : fromIndex = fromIndex,
  +      toIndex = toIndex,
  +      colors = colors ?? const [Colors.blueGrey],
  +      gradientFrom = gradientFrom ?? const Offset(0, 0),
  +      gradientTo = gradientTo ?? const Offset(1, 0),
  +      gradientColorStops = gradientColorStops;
   
     /// Lerps a [BetweenBarsData] based on [t] value, check [Tween.lerp].
     static BetweenBarsData lerp(BetweenBarsData a, BetweenBarsData b, double t) {
  
positive.code:   /// you can override it with your custom data.
    /// [show] determines showing label or not.
    VerticalLineLabel({
      EdgeInsets padding = const EdgeInsets.all(6),
      TextStyle style = const TextStyle(
        color: Colors.black,
        fontWeight: FontWeight.bold,
        fontSize: 14,
      ),
      Alignment alignment = Alignment.bottomRight,
      bool show = false,
      this.labelResolver = VerticalLineLabel.defaultLineLabelResolver,
    }) : super(show: show, padding: padding, style: style, alignment: alignment);
  
    /// Lerps a [VerticalLineLabel] based on [t] value, check [Tween.lerp].
    static VerticalLineLabel lerp(VerticalLineLabel a, VerticalLineLabel b, double t) {
  
negative.code:   /// you can override it with your custom data.
    /// /// [show] determines showing label or not.
    HorizontalLineLabel({
      EdgeInsets padding,
      TextStyle style,
      Alignment alignment,
      bool show = false,
      String Function(HorizontalLine) labelResolver,
    })
      : labelResolver = labelResolver ?? HorizontalLineLabel.defaultLineLabelResolver,
        super(
        show: show,
        padding: padding ?? const EdgeInsets.all(6),
        style: style ?? const TextStyle(
          color: Colors.black,
          fontWeight: FontWeight.bold,
          fontSize: 14,
        ),
        alignment: alignment ?? Alignment.topLeft,
      );
  
    /// Lerps a [HorizontalLineLabel] based on [t] value, check [Tween.lerp].
    static HorizontalLineLabel lerp(HorizontalLineLabel a, HorizontalLineLabel b, double t) {
  