code: def dir_tails_target(self, rr_id) -> str:
          
  
          return join(self.dir_tails_top(rr_id), rev_reg_id2cred_def_id(rr_id))
docs: Return target directory for revocation registry and tails file production.
  
          :param rr_id: revocation registry identifier
          :return: tails target directory