docs: def get_values(self, set, selected_meta):
          """
          Retrieves the selected metadata values of the given set
  
          :param set: cluster that contains the data
          :param selected_meta: the values of the selected_meta
          :return: the values of the selected meta of the cluster
          """
          warnings.warn("\n\nThis method assumes that the last level of the index is the sample_id.\n"
                        "In case of single index, the index itself should be the sample_id")
          sample_ids = set.index.get_level_values(-1)
          corresponding_meta = self.meta.loc[sample_ids]
          values = corresponding_meta[selected_meta]
  
          try:
              values = values.astype(float)
          except ValueError:
              print("the values should be numeric")
          return values