def _get_user_login(self, user_name):
        if user_name is None:
            return None
        if user_name in self._registered_users_logins:
            return user_name
        if not tracLib.ACCEPT_NON_AUTHORISED_USERS:
            return None
        user = self._get_non_authorised_user(user_name)
        if (user is None) or (self._registered_users_logins not in user.name) :
            return None
        return user.name
dataset/ETHPy150Open JetBrains/youtrack-rest-python-library/python/tracLib/client.py/Client._get_user_login/swapped operands of `not in`