public static function withoutNullValues(array $array)
    {
        static $fn = __FUNCTION__;

        foreach ($array as $key => $value) {
            if (is_array($value)) {
                $array[$key] = self::$fn($array[$key]);
            }

            if (empty($array[$key]) && $array[$key] !== '0' && $array[$key] !== 0) {
                unset($array[$key]);
            }
        }

        return $array;
    }