code: def rollback(self):
          
          self._tx_active = False
          return self._channel.rpc_request(specification.Tx.Rollback())
docs: Abandon the current transaction.
  
              Rollback all messages published during the current transaction
              session to the remote server.
  
              Note that all messages published during this transaction session
              will be lost, and will have to be published again.
  
              A new transaction session starts as soon as the command has
              been executed.
  
          :return: