public static function expand(array $array, string $prepend = ''): array
    {
        $results = [];

        if ($prepend) {
            $prepend .= '.';
        }

        foreach ($array as $key => $value) {
            if ($prepend) {
                $pos = strpos($key, $prepend);

                if ($pos === 0) {
                    $key = substr($key, strlen($prepend));
                }
            }

            $results = static::set($results, $key, $value);
        }

        return $results;
    }