var currentId = null;

Effect.Accordion = function (contentId) {
    var slideDown = 0.3;
    var slideUp = 0.3;

    contentId = $(contentId);

    if (currentId != contentId) {
            if (currentId == null) {
                    new Effect.SlideDown(contentId, {duration: slideDown});
                    } else {
                    new Effect.SlideUp(currentId, {duration: slideUp});
                    new Effect.SlideDown(contentId, {duration: slideDown});
            }
            currentId = contentId; 
    } else {
            new Effect.SlideUp(currentId, {duration: slideUp});
            currentId = null;
    }
};