code: function(element, className, bool) {
      return (bool ? CSSCore.addClass : CSSCore.removeClass)(element, className);
    }
docs: Helper to add or remove a class from an element based on a condition.
  
  @param {DOMElement} element the element to set the class on
  @param {string} className the CSS className
  @param {*} bool condition to whether to add or remove the class
  @return {DOMElement} the element passed in