function markActiveLink(menuContainerSelector, classToApply) {

    //Look through all the links in the sidebar 
    var matched = $(menuContainerSelector + " a").filter(function () {

        //Take the current URL and split it into chunks at each slash 
        var currentURL = window.location.toString().split("/");

        //return true if the bit after the last slash is the current page name 
        return $(this).attr("href") == currentURL[currentURL.length - 1];

        //when the filter function is done, you're left with the links that match. 
    });

    matched.parent().parent().parent().children("a").addClass(classToApply);
}