public static function getAllIniPartCacheSubKeys() : array
    {
        $subKeys = [];
        $chars = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'];

        foreach ($chars as $charOne) {
            foreach ($chars as $charTwo) {
                foreach ($chars as $charThree) {
                    $subKeys[] = $charOne . $charTwo . $charThree;
                }
            }
        }

        return $subKeys;
    }