docs: def register_enum_for_json(*args, **kwargs) -> Any:
      """
      Class decorator to register ``Enum``-derived classes with our JSON system.
      See comments/help for ``@register_for_json``, above.
      """
      if len(args) == 1 and len(kwargs) == 0 and callable(args[0]):
          # called as @register_enum_for_json
          cls = args[0]  # type: ClassType
          register_class_for_json(
              cls,
              obj_to_dict_fn=enum_to_dict_fn,
              dict_to_obj_fn=dict_to_enum_fn
          )
          return cls
      else:
          # called as @register_enum_for_json(*args, **kwargs)
          raise AssertionError("Use as plain @register_enum_for_json, "
                               "without arguments")