code: def add_series(self, name, values=(), number_format=None):
          
          series_data = CategorySeriesData(self, name, number_format)
          self.append(series_data)
          for value in values:
              series_data.add_data_point(value)
          return series_data
docs: Add a series to this data set entitled *name* and having the data
          points specified by *values*, an iterable of numeric values.
          *number_format* specifies how the series values will be displayed,
          and may be a string, e.g. '#,##0' corresponding to an Excel number
          format.