docs: def _get_function_wrapper(
          self, func: typing.Callable[..., typing.Union["typing.Awaitable[typing.Any]", typing.Any]]
      ) -> typing.Callable[..., typing.Any]:
          """Here should be constructed and returned real decorator.
  
          :param func: Wrapped function
          :type func: typing.Callable[..., typing.Union[typing.Awaitable, typing.Any]]
          :rtype: typing.Callable
          """
          raise NotImplementedError()