_scriptNode = function(url, win, attributes) {
        var o = {
            id: Y.guid(),
            type: TYPE_JS
        };

        if (attributes) {
            Y.mix(o, attributes);
        }

        o.src = url;

        return _node('script', o, win);
    }
Generates a script node
@method _scriptNode
@param {string} url the url for the script file.
@param {Window} win optional window to create the node in.
@param {object} attributes optional attributes collection to apply to the
new node.
@return {HTMLElement} the generated node.
@private