code: public PieSeries addSeries(String seriesName, Number value) {
  
      PieSeries series = new PieSeries(seriesName, value);
  
      if (seriesMap.keySet().contains(seriesName)) {
        throw new IllegalArgumentException(
            "Series name >"
                + seriesName
                + "< has already been used. Use unique names for each series!!!");
      }
      seriesMap.put(seriesName, series);
  
      return series;
    }
docs: Add a series for a Pie type chart
  
  @param seriesName
  @param value
  @return