code: def retrieve_dataset_handles_or_version_numbers_of_all_versions(self, drs_id, prefix):
          '''
          :return: Dict. Should never return None.
          :raise: SolrSwitchedOff
          :raise SolrError: If ...
          '''
          self.__reset_error_messages()
          response_json = self.__ask_solr_for_handles_or_version_numbers_of_all_versions(drs_id)
          result_dict = self.__parse_result_handles_or_version_numbers_of_all_versions(response_json, prefix)
          return result_dicf retrieve_dataset_handles_or_version_numbers_of_all_versions(self, drs_id, prefix):
          '''
          :return: Dict. Should never return None.
          :raise: SolrSwitchedOff
          :raise SolrError: If ...
          '''
          self.__reset_error_messages()
          response_json = self.__ask_solr_for_handles_or_version_numbers_of_all_versions(drs_id)
          result_dict = self.__parse_result_handles_or_version_numbers_of_all_versions(response_json, prefix)
          return result_dict
docs: :return: Dict. Should never return None.
          :raise: SolrSwitchedOff
          :raise SolrError: If ...