League\CommonMark\Util\Html5Entities::fromDecimal PHP Method

    public static function fromDecimal($number)
    {
        // Only convert code points within planes 0-2, excluding NULL
        if (empty($number) || $number > 0x2ffff) {
            return self::fromHex('fffd');
        }
        $entity = '&#' . $number . ';';
        $converted = mb_decode_numericentity($entity, [0x0, 0x2ffff, 0, 0xffff], 'UTF-8');
        if ($converted === $entity) {
            return self::fromHex('fffd');
        }
        return $converted;
    }