def _reader(self, allow_async=False):
        if self.mode is None:
            self.mode = _READER
        elif self.mode > _ASYNC_READER and not allow_async:
            raise TypeError(
                "Can't upgrade an ASYNC_READER transaction "
                "to a READER mid-transaction")
dataset/ETHPy150Open openstack/oslo.db/oslo_db/sqlalchemy/enginefacade.py/_TransactionContext._reader/operator `is` -> `>`