'Try to retrieve a single message off ``queue``.'

def _get(self, queue):

    q = self._new_queue(queue)
    rs = q.pop(1)
    if rs[u'items']:
        m = rs[u'items'][0]
        payload = loads(bytes_to_str(m[u'body']))
        if (queue in self._noack_queues):
            q.message(m[u'id']).delete()
        else:
            payload[u'properties'][u'delivery_info'].update({u'slmq_message_id': m[u'id'], u'slmq_queue_name': q.name})
        return payload
    raise Empty()
