def reply(self, reply, orig_req):
        """Send an asynchronous reply to an earlier request.

        Parameters
        ----------
        reply : Message object
            The reply message to send.
        orig_req : Message object
            The request message being replied to. The reply message's
            id is overridden with the id from orig_req before the
            reply is sent.

        """
        assert (reply.mtype == Message.REPLY)
        assert reply.name == orig_req.name
        reply.mid = orig_req.mid
        return self._send_message(reply)