public static function get()
    {
        mt_srand((int) (microtime(true) * 1000));

        $b = md5(uniqid(mt_rand(), true), true);
        $b[6] = chr((ord($b[6]) & 0x0F) | 0x40);
        $b[8] = chr((ord($b[8]) & 0x3F) | 0x80);

        return implode('-', unpack('H8a/H4b/H4c/H4d/H12e', $b));
    }