code: function (htmlElem, properties, cfg) {
                  var elem = this._getHTMLElement(htmlElem);
                  if (elem == null) {
                      this.$logWarn(this.INVALID_HTML_ELEMENT);
                      return null;
                  }
                  if (aria.utils.Dom.getStyle(elem, "display") == "none") {
                      return this.show(elem, properties, cfg);
                  } else {
                      return this.hide(elem, properties, cfg);
                  }
              }
docs: Hides or shows an HTML element. <br>
  it hides (if displayed) or shows (if hidden) an element animating the properties listed in properties
  parameter, or animating the opacity (if properties parameter is empty)
  @param {HTMLElement|String} element to be animated (or its id)
  @param {Array} CSS properties list; values can be: "height","width","opacity"
  @param {Object} cfg animation configuration
  @return {String} animation ID