docs: def resend_transaction_frames(self, connection, transaction):
          """
          Resend the messages that were ACK'd in specified transaction.
  
          This is called by the engine when there is an abort command.
  
          @param connection: The client connection that aborted the transaction.
          @type connection: L{coilmq.server.StompConnection}
  
          @param transaction: The transaction id (which was aborted).
          @type transaction: C{str}
          """
          for frame in self._transaction_frames[connection][transaction]:
              self.send(frame)