function toggle_menu(klass) {
    elems = $('.' + klass)
    for (i=0; i < elems.length; i++) {
        show = elems[i].style.display
        if (show == "none") {
            elems[i].style.display = ""
        }
        else {
            elems[i].style.display = "none"
        }
    }
}