anchor.diff:    /// It draws an image in left side of the chart, use [sizedPicture] for vectors,
     /// or [image] for any kind of image.
     HorizontalLine({
  -    this.y,
  -    this.label,
  +    @required this.y,
  +    this.label = const HorizontalLineLabel(),
       Color color = Colors.black,
       double strokeWidth = 2,
       List<int> dashArray,
  
positive.code:   /// Draws a title on the line, align it with [alignment] over the line,
    /// applies [padding] for spaces, and applies [style] for changing color,
    /// size, ... of the text.
    FlLineLabel({this.padding, this.style, this.alignment});
  
  }
  
  
negative.code:   /// size, ... of the text.
    /// Drawing text will retrieve through [labelResolver],
    /// you can override it with your custom data.
    const VerticalLineLabel({
      EdgeInsets padding = const EdgeInsets.all(6),
      TextStyle style = const TextStyle(
        color: Colors.black,
        fontWeight: FontWeight.bold,
        fontSize: 14,
      ),
      Alignment alignment = Alignment.bottomRight,
      this.labelResolver = VerticalLineLabel.defaultLineLabelResolver,
    }) : super(padding: padding, style: style, alignment: alignment);
  