private function applyTransaction(\stdClass $obj_request) {
        if(null !== $this->str_next_transaction) {
            $obj_request->readOptions = (object)[
                // 'readConsistency' => $options->getReadConsistency(),
                "transaction" => $this->str_next_transaction
            ];
            $this->str_next_transaction = null;
        }
        return $obj_request;
    }