public static function randomString(int $length): string
    {
        $characters = 'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz0123456789';
        $string = '';
        for ($i = 0; $i < $length; $i++) {
            $string .= $characters[rand(0, strlen($characters) - 1)];
        }
        return $string;
    }