docs: def group_statistics(self, group, selected_meta, stat_code='mean'):
          """
          Provides statistics of a group based on the meta data selected.
  
          :param group:The result of a classification or clustering.rst or biclustering algorithm
          :param selected_meta: The metadata that we are interested in
          :param stat_code: 'mean' for mean or 'variance' for variance or 'std' for standard deviation
          :return: returns the statistics properties of the selected metadata
          """
          values = self.get_values(group, selected_meta)
          if stat_code == 'mean':
              res = statistics.mean(values)
          elif stat_code == 'variance':
              res = statistics.variance(values)
          elif stat_code == 'std':
              res = statistics.stdev(values)
          return res