/**
 * @return {string}
 */
S4 = function () {
    return (((1 + Math.random()) * 0x10000) | 0).toString(16).substring(1);
};


/**
 * @return {string}
 */
GUID = function () {
    return (S4() + S4() + "-" + S4() + "-4" + S4().substr(0, 3) + "-" + S4() + "-" + S4() + S4() + S4()).toLowerCase();
};