docs: def _find_folders(self, folder_name):
          """Return a list of sub-directories."""
          found_folders = []
          for app_config in apps.get_app_configs():
              folder_path = os.path.join(app_config.path, folder_name)
              if os.path.isdir(folder_path):
                  found_folders.append(folder_path)
          return found_folders