code: function(el, className) {
              return Y.Dom.batch(el, Y.Dom._addClass, className);
          }
docs: Adds a class name to a given element or collection of elements.
  @method addClass
  @param {String | HTMLElement | Array} el The element or collection to add the class to
  @param {String} className the class name to add to the class attribute
  @return {Boolean | Array} A pass/fail boolean or array of booleans