Publish a message to a given pubsub topic

        Publishing will publish the given payload (string) to
        everyone currently subscribed to the given topic.

        All data (including the id of the publisher) is automatically
        base64 encoded when published.

        .. code-block:: python

            # publishes the message 'message' to the topic 'hello'
            >>> c.pubsub_pub('hello', 'message')
            []

        Parameters
        ----------
        topic : str
            Topic to publish to
        payload : Data to be published to the given topic

        Returns
        -------
            list : empty list

def pubsub_pub(self, topic, payload, **kwargs):
        """Publish a message to a given pubsub topic

        Publishing will publish the given payload (string) to
        everyone currently subscribed to the given topic.

        All data (including the id of the publisher) is automatically
        base64 encoded when published.

        .. code-block:: python

            # publishes the message 'message' to the topic 'hello'
            >>> c.pubsub_pub('hello', 'message')
            []

        Parameters
        ----------
        topic : str
            Topic to publish to
        payload : Data to be published to the given topic

        Returns
        -------
            list : empty list
        """
        args = (topic, payload)
        return self._client.request('/pubsub/pub', args,
                                    decoder='json', **kwargs)