Create or update Media objects related to a post.

        :param bulk_mode: If True, minimize db operations by bulk creating post objects
        :param api_post: the API data for the Post
        :param post_media_attachments: a mapping of Media objects keyed by post ID
        :return: None

def process_post_media_attachments(self, bulk_mode, api_post, post_media_attachments):
        """
        Create or update Media objects related to a post.

        :param bulk_mode: If True, minimize db operations by bulk creating post objects
        :param api_post: the API data for the Post
        :param post_media_attachments: a mapping of Media objects keyed by post ID
        :return: None
        """
        post_media_attachments[api_post["ID"]] = []

        for api_attachment in six.itervalues(api_post["attachments"]):
            attachment = self.process_post_media_attachment(bulk_mode, api_attachment)
            if attachment:
                post_media_attachments[api_post["ID"]].append(attachment)