anchor.diff:      initSuperMinMaxValues(maxY);
     }
   
  -  /// we have to tell [AxisChartData] how much is our
  -  /// minX, maxX, minY, maxY, values.
  -  /// here we get them in our constructor, but if each of them was null,
  -  /// we calculate it with the barGroups, and barRods data.
  +  /// fills [minX], [maxX], [minY], [maxY] if they are null,
  +  /// based on the provided [barGroups].
     void initSuperMinMaxValues(
       double maxY,
     ) {
  
positive.code:   }
  }
  
  /***** BarChartRodData *****/
  
  /// This class holds data to show a single rod,
  /// rod is a vertical bar line,
  class BarChartRodData {
    final double y;
    final Color color;
    final double width;
    final BorderRadius borderRadius;
    final BackgroundBarChartRodData backDrawRodData;
    final List<BarChartRodStackItem> rodStackItem;
  
    BarChartRodData({
      this.y,
      this.color = Colors.blueAccent,
  
negative.code:   }
  }
  
  /// defines arrangement of [barGroups], check [MainAxisAlignment] for more details.
  enum BarChartAlignment {
    start,
    end,
  