anchor.diff:    /// [show] determines showing or hiding all titles,
     /// [leftTitles], [topTitles], [rightTitles], [bottomTitles] defines
     /// side titles of left, top, right, bottom sides respectively.
  -  const FlTitlesData({
  -    this.show = true,
  -    this.leftTitles = const SideTitles(reservedSize: 40, showTitles: true),
  -    this.topTitles = const SideTitles(reservedSize: 6),
  -    this.rightTitles = const SideTitles(
  -      reservedSize: 40,
  -    ),
  -    this.bottomTitles = const SideTitles(reservedSize: 22, showTitles: true),
  -  });
  +  FlTitlesData({
  +    bool show,
  +    SideTitles leftTitles,
  +    SideTitles topTitles,
  +    SideTitles rightTitles,
  +    SideTitles bottomTitles,
  +  })
  +    : show = show ?? true,
  +      leftTitles = leftTitles ?? SideTitles(reservedSize: 40, showTitles: true),
  +      topTitles = topTitles ?? SideTitles(reservedSize: 6),
  +      rightTitles = rightTitles ?? SideTitles(reservedSize: 40),
  +      bottomTitles = bottomTitles ?? SideTitles(reservedSize: 22, showTitles: true);
   
     /// Lerps a [FlTitlesData] based on [t] value, check [Tween.lerp].
     static FlTitlesData lerp(FlTitlesData a, FlTitlesData b, double t) {
  
positive.code:   /// [show] determines showing or hiding all titles,
    /// [leftTitle], [topTitle], [rightTitle], [bottomTitle] determines
    /// title for left, top, right, bottom axis sides respectively.
    const FlAxisTitleData({
      this.show = true,
      this.leftTitle = const AxisTitle(reservedSize: 16),
      this.topTitle = const AxisTitle(reservedSize: 16),
      this.rightTitle = const AxisTitle(reservedSize: 16),
      this.bottomTitle = const AxisTitle(reservedSize: 16),
    });
  
    /// Lerps a [FlAxisTitleData] based on [t] value, check [Tween.lerp].
    static FlAxisTitleData lerp(FlAxisTitleData a, FlAxisTitleData b, double t) {
  
negative.code:   /// it is a circular array of dash offsets and lengths.
    /// For example, the array `[5, 10]` would result in dashes 5 pixels long
    /// followed by blank spaces 10 pixels long.
    FlLine({Color color, double strokeWidth = 2, List<int> dashArray})
      :
        color = color ?? Colors.black,
        strokeWidth = strokeWidth ?? 2,
        dashArray = dashArray;
  
    /// Lerps a [FlLine] based on [t] value, check [Tween.lerp].
    static FlLine lerp(FlLine a, FlLine b, double t) {
  