anchor.diff:  
         for (final category in singleCategoryModel.categories) {
           seriesData.add(new ChartInnerDataSets(
  -          name: category,
  +          name: category.toString(),
             y: singleCategoryModel.getValue(category),
             color: singleCategoryModel.getValueColor(category),
             visible: singleCategoryModel.getValueColor(category) != null));
  
positive.code:         data: data[series]));
  
      return list;
    }
  
    CategoryModel get model => super.model;
  
    void set model(ChartModel model) {
      if (model is! CategoryModel)
        return;
  
      super.model = model;
    }
  }
  
  
negative.code: 
  }
  
  abstract class ColumnChart<S extends Comparable, C extends Comparable> implements Chart<S, C, CategoryModel<S, C>> {
    factory ColumnChart({String titleText: '', String subtitleText: '',
      dynamic width, dynamic height, ChartXAxis xAxis, ChartYAxis yAxis})
      => new _ColumnChartImpl<S, C>(titleText: titleText, subtitleText: subtitleText,
          width: width, height: height, xAxis: xAxis, yAxis: yAxis);
  }
  
  abstract class DonutChart<S extends Comparable, C extends Comparable> extends Chart<S, C, DonutModel<S, C>> {
    factory DonutChart({String titleText: '', String subtitleText: '',
    dynamic width, dynamic height, ChartXAxis xAxis, ChartYAxis yAxis})
    => new _DonutChartImpl<S, C>(titleText: titleText, subtitleText: subtitleText,
        width: width, height: height, xAxis: xAxis, yAxis: yAxis);
  }
  
  abstract class AreaChart<S extends Comparable, C extends Comparable> extends Chart<S, C, CategoryModel<S, C>> {
    factory AreaChart({String titleText: '', String subtitleText: '',
    dynamic width, dynamic height, ChartXAxis xAxis, ChartYAxis yAxis})
    => new _AreaChartImpl<S, C>(titleText: titleText, subtitleText: subtitleText,
        width: width, height: height, xAxis: xAxis, yAxis: yAxis);
  }
  
  abstract class _BaseChartImpl<S extends Comparable, C extends Comparable, T extends ChartModel<S, C>> implements Chart<S, C, T> {
  
    final String type;
    final Element element = _createUncheckedHtml('<div class="highchart-wrap"></div>');
  