private static function unescapeUnicode($sData)
    {
        return preg_replace_callback(
            '/\\\\u([0-9a-f]{4})/i',
            function (array & $aMatches) {
                $sSym = mb_convert_encoding(
                    pack('H*', $aMatches[1]),
                    'UTF-8',
                    'UTF-16'
                );
                return $sSym;
            },
            $sData
        );
    }