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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def send(self, message):
 """ Sends a MESSAGE frame to an eligible subscriber connection. Note that this method will modify the incoming message object to add a message-id header (if not present) and to change the command to 'MESSAGE' (if it is not). @param message: The message frame. @type message: C{stompclient.frame.Frame} """

        dest = message.headers.get('destination')
        if not dest:
            raise ValueError(
                "Cannot send frame with no destination: %s" % message)

        message.cmd = 'message'

        message.headers.setdefault('message-id', str(uuid.uuid4()))

        # Grab all subscribers for this destination that do not have pending
        # frames
        subscribers = [s for s in self._queues[dest]
                       if s not in self._pending]

        if not subscribers:
            self.log.debug(
                "No eligible subscribers; adding message %s to queue %s" % (message, dest))
            self.store.enqueue(dest, message)
        else:
            selected = self.subscriber_scheduler.choice(subscribers, message)
            self.log.debug("Delivering message %s to subscriber %s" %
                           (message, selected))
            self._send_frame(selected, message)