public function killCursors($cursors, $conn)
    {
        if (!$cursors) {
            $cursors = [];
        }

        $this->request(
            self::OP_KILL_CURSORS,
            "\x00\x00\x00\x00" . pack('V', sizeof($cursors)) . implode('', $cursors),
            false,
            $conn
        );
    }