def _update_job(self, target, args, kwargs):
        """Specify the function this async job is to execute when run."""
        target_path, options = get_function_path_and_options(target)

        assert isinstance(args, (tuple, list)) or args is None
        assert isinstance(kwargs, dict) or kwargs is None

        if options:
            self.update_options(**options)

        self._options['job'] = (target_path, args, kwargs)