docs: def return_real_id(self):
          """
          Returns a list of real_id's
  
          Parameters
          ----------
  
          Returns
          -------
          A list of real_id values for the dataset (a real_id is the filename minus the suffix and prefix)
          """
          if self._prepopulated is False:
              raise errors.EmptyDatabase(self.dbpath)
          else:
              return return_real_id_base(self.dbpath, self._set_object)