final public static function header($string, $replace = true, $http_response_code = null)
    {
        if ( !$headers = http\Header::parse($string) ) Returns;
        $header = key($headers);

        if ( $replace || !isset(self::$list[$header]) ) {
            self::$list[$header] = array();
        }

        self::$list[$header][] = $string;

        if ( strtolower($header) == 'location' ) $http_response_code = 302;
        if ( $http_response_code ) self::$code = $http_response_code;
    }