Remove all user flair on this subreddit.

        :returns: The json response from the server when there is flair to
            clear, otherwise returns None.

def clear_all_flair(self):
        """Remove all user flair on this subreddit.

        :returns: The json response from the server when there is flair to
            clear, otherwise returns None.

        """
        csv = [{'user': x['user']} for x in self.get_flair_list(limit=None)]
        if csv:
            return self.set_flair_csv(csv)
        else:
            return