anchor.diff:      borderData ??= FlBorderData();
     }
   
  -  /// this function is used for animate between current and target data,
  -  /// used in the [BaseChartDataTween]
     BaseChartData lerp(BaseChartData a, BaseChartData b, double t);
   }
   
  -/***** BorderData *****/
  -
  -/// Border Data that contains
  -/// used the [Border] class to draw each side of border.
  +/// Holds data to drawing border around the chart.
   class FlBorderData {
     final bool show;
     Border border;
   
  +  /// [show] Determines showing or hiding border around the chart.
  +  /// [border] Determines the visual look of 4 borders, see [Border].
     FlBorderData({
       this.show = true,
       this.border,
  
positive.code:       titleText: b.titleText,
        reservedSize: lerpDouble(a.reservedSize, b.reservedSize, t),
        textStyle: TextStyle.lerp(a.textStyle.copyWith(fontSize: a.textStyle.fontSize),
            b.textStyle.copyWith(fontSize: b.textStyle.fontSize), t),
        textAlign: b.textAlign,
        margin: lerpDouble(a.margin, b.margin, t),
      );
    }
  }
  
  /***** TitlesData *****/
  
  /// we use this typedef to determine which titles
  /// we should show (according to the value),
  /// we pass the value and get a boolean to show the title for that value.
  typedef GetTitleFunction = String Function(double value);
  
  String defaultGetTitle(double value) {
    return '$value';
  }
  
  /// This class is responsible to hold data about showing titles.
  /// titles show on the each side of chart
  class FlTitlesData {
    final bool show;
  
    final SideTitles leftTitles, topTitles, rightTitles, bottomTitles;
  
    const FlTitlesData({
      this.show = true,
      this.leftTitles = const SideTitles(reservedSize: 40, showTitles: true),
  
negative.code:   }
  }
  
  /// Holds data for showing title of each side of charts.
  class AxisTitle {
  
    /// You can show or hide it using [showTitle],
    final bool showTitle;
  
    /// Defines how much space it needed to draw.
    final double reservedSize;
  
    /// Determines the style of this.
    final TextStyle textStyle;
  
    /// Determines alignment of this title.
    final TextAlign textAlign;
  
    /// Determines margin of this title.
    final double margin;
  
    /// Determines the showing text.
    final String titleText;
  
    /// You can show or hide it using [showTitle],
    /// [titleText] determines the text, and
    /// [textStyle] determines the style of this.
    /// [textAlign] determines alignment of this title,
    /// [BaseChartPainter] uses [reservedSize] for assigning
    /// a space for drawing this side title, it used for
    /// some calculations.
    /// [margin] determines margin of this title.
    const AxisTitle({
      this.showTitle = false,
      this.titleText = '',
  