<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def publish(self, payload, **kwargs):
 """ Publish a message. """

        publish_kwargs = self.publish_kwargs.copy()

        # merge headers from when the publisher was instantiated
        # with any provided now; "extra" headers always win
        headers = publish_kwargs.pop('headers', {}).copy()
        headers.update(kwargs.pop('headers', {}))
        headers.update(kwargs.pop('extra_headers', {}))

        use_confirms = kwargs.pop('use_confirms', self.use_confirms)
        transport_options = kwargs.pop('transport_options',
                                       self.transport_options
                                       )
        transport_options['confirm_publish'] = use_confirms

        delivery_mode = kwargs.pop('delivery_mode', self.delivery_mode)
        mandatory = kwargs.pop('mandatory', self.mandatory)
        priority = kwargs.pop('priority', self.priority)
        expiration = kwargs.pop('expiration', self.expiration)
        serializer = kwargs.pop('serializer', self.serializer)
        compression = kwargs.pop('compression', self.compression)
        retry = kwargs.pop('retry', self.retry)
        retry_policy = kwargs.pop('retry_policy', self.retry_policy)

        declare = self.declare[:]
        declare.extend(kwargs.pop('declare', ()))

        publish_kwargs.update(kwargs)  # remaining publish-time kwargs win

        with get_producer(self.amqp_uri,
                          use_confirms,
                          self.ssl,
                          transport_options,
                          ) as producer:
            try:
                producer.publish(
                    payload,
                    headers=headers,
                    delivery_mode=delivery_mode,
                    mandatory=mandatory,
                    priority=priority,
                    expiration=expiration,
                    compression=compression,
                    declare=declare,
                    retry=retry,
                    retry_policy=retry_policy,
                    serializer=serializer,
                    **publish_kwargs
                )
            except ChannelError as exc:
                if "NO_ROUTE" in str(exc):
                    raise UndeliverableMessage()
                raise

            if mandatory:
                if not use_confirms:
                    warnings.warn(
                        "Mandatory delivery was requested, but "
                        "unroutable messages cannot be detected without "
                        "publish confirms enabled."
                    )