max-age=" + 60 * 60 *
                       24 * lifespan_in_days +
                       "; path=/" + domain_string ;
}
function get_cookie ( cookie_name )
{
    // http://www.thesitewizard.com/javascripts/cookies.shtml
    var cookie_string = document.cookie ;
    if (cookie_string.length != 0) {
        var cookie_value = cookie_string.match (
                        '(^|;)[\s]*' +
                        cookie_name +
                        '=([^;]*)' );
        return decodeURIComponent ( cookie_val