code: def dir_tails(self, rr_id: str) -> str:
          
  
          LOGGER.debug('HolderProver.dir_tails >>>')
  
          if not ok_rev_reg_id(rr_id):
              LOGGER.debug('HolderProver.dir_tails <!< Bad rev reg id %s', rr_id)
              raise BadIdentifier('Bad rev reg id {}'.format(rr_id))
  
          rv = Tails.dir(self._dir_tails, rr_id)
          LOGGER.debug('HolderProver.dir_tails <<< %s', rv)
          return rv
docs: Return path to the correct directory for the tails file on input revocation registry identifier.
  
          :param rr_id: revocation registry identifier of interest
          :return: path to tails dir for input revocation registry identifier