docs: 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)