public static function stringToArray(?string $string): array {
        $result = [];
        $strLen = \strlen($string);
        if (null === $string) return $result;
        if (1 === $strLen) {
            $result[] = $string;
            return $result;
        }
        for ($i = 0; $i < $strLen; $i++) {
            $result[] = $string[$i];
        }
        return $result;
    }