docs: def filesystem_repository(_context, name=None, make_default=False,
                            aggregate_class=None, repository_class=None,
                            directory=None, content_type=None):
      """
      Directive for registering a file-system based repository.
      """
      cnf = {}
      if not directory is None:
          cnf['directory'] = directory
      if not content_type is None:
          cnf['content_type'] = content_type
      _repository(_context, name, make_default,
                  aggregate_class, repository_class,
                  REPOSITORY_TYPES.FILE_SYSTEM, 'add_filesystem_repository',
                  cnf)