/// `getWithFailover` takes a list of URLs, and walks through them
/// until one succeeds.
$.getWithFailover = function(urls, k) {
    $.ajax({url:urls.shift(), success:k, error:retry});
    function retry() {
        if (urls.length)
            $.ajax({url:urls.shift(), success:k, error:retry});
    }
};$.getWithFailover(
    ['services/error', 'services/error', 'services/time'],
    log);