code: public XYSeries getSeries( String seriesName ) {
          XYSeries series = new XYSeries(seriesName);
          dataset.addSeries(series);
          return series;
      }
docs: Get {@link Series} to be populated.
  
  <p>Teh series is added to the dataset.
  
  @param seriesName the name of the series to add.
  @return the {@link XYSeries} to use.