code: def message_archive_per_category(self, project_id, category_id):
          
          path = '/projects/%u/msg/cat/%u/archive' % (project_id, category_id)
          return self._request(path)
docs: This will return a summary record for each message in a particular
          category. (Note that a summary record includes only a few bits of
          information about a post, not the complete record.)