YUI.stamp

    stamp: function(o, readOnly) {
        var uid;
        if (!o) {
            return o;
        }
 
        // IE generates its own unique ID for dom nodes
        // The uniqueID property of a document node returns a new ID
        if (o.uniqueID && o.nodeType && o.nodeType !== 9) {
            uid = o.uniqueID;
        } else {
            uid = (typeof o === 'string') ? o : o._yuid;
        }
 
        if (!uid) {
            uid = this.guid();
            if (!readOnly) {
                try {
                    o._yuid = uid;
                } catch (e) {
                    uid = null;
                }
            }
        }
        return uid;
    },