anchor.diff:  /// [indicatorBelowLine] we draw a vertical line below of the touched spot
   /// [touchedSpotDotData] we draw a larger dot on the touched spot to bold it
   class TouchedSpotIndicatorData {
  -
     /// Determines line's style.
     final FlLine indicatorBelowLine;
   
  
positive.code: /// [LineChart] draws some [HorizontalLine] (set by [LineChartData.extraLinesData]),
  /// in below or above of everything, it draws from left to right side of the chart.
  class HorizontalLine extends FlLine {
  
    /// Draws from left to right of the chart using the [y] value.
    final double y;
  
  
negative.code: /// [LineChart] draws some [VerticalLine] (set by [LineChartData.extraLinesData]),
  /// in below or above of everything, it draws from bottom to top side of the chart.
  class VerticalLine extends FlLine {
    /// Draws from bottom to top of the chart using the [x] value.
    final double x;
  
  