Create or update Categories 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_categories: a mapping of Categories keyed by post ID
        :return: None

def process_post_categories(self, bulk_mode, api_post, post_categories):
        """
        Create or update Categories 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_categories: a mapping of Categories keyed by post ID
        :return: None
        """
        post_categories[api_post["ID"]] = []
        for api_category in six.itervalues(api_post["categories"]):
            category = self.process_post_category(bulk_mode, api_category)
            if category:
                post_categories[api_post["ID"]].append(category)