docs: def sort_by(items, attr):
      """
      General sort filter - sorts by either attribute or key.
      """
      def key_func(item):
          try:
              return getattr(item, attr)
          except AttributeError:
              try:
                  return item[attr]
              except TypeError:
                  getattr(item, attr)  # Reraise AttributeError
      return sorted(items, key=key_func)