async def _rollback(self):
    try:
        query = self._make_rollback_query()
        try:
            (await self._connection_impl.privileged_execute(query))
        except BaseException:
            self._state = TransactionState.FAILED
            raise
        else:
            self._state = TransactionState.ROLLEDBACK
    finally:
        self._maybe_return()
        if (self._pool is not None):
            (await self._pool._release(self._connection))
async def _rollback(self):
    try:
        query = self._make_rollback_query()
        try:
            (await self._connection_impl.privileged_execute(query))
        except BaseException:
            self._state = TransactionState.FAILED
            raise
        else:
            self._state = TransactionState.ROLLEDBACK
    finally:
        self._maybe_return()
        if (self._pool is not None):
            (await self._pool._release(self._connection))