public static function header($headers)
    {
        if (is_array($headers)) {
            // if pass array
            foreach ($headers as $header) {
                if (FALSE === Http::header($header)) {
                    throw new \InvalidArgumentException("Header $header is invalid!");
                }
            }
            return;
        }
        // pass string
        if (FALSE === Http::header($headers)) {
            throw new \InvalidArgumentException("Header $headers is invalid!");
        }
    }