def _make_user_dict(self, username):
        """
        Processes a Twitter User object, exporting as a nested dictionary.
        Complex values (i.e. objects that aren't int, bool, float, str, or
        a collection of such) are converted to strings (i.e. using __str__
        or __repr__). To access user data only, use make_user_dict(username)['_json'].

        :param username: A Twitter username string.
        :return: A nested dictionary of user data.
        """
        user = self._api.get_user(username)
        return self._make_object_dict(user)