Element.addMethods('iframe', {
document: function(element) {
  element = $(element);
  if (element.contentWindow)
      return element.contentWindow.document;
  else if (element.contentDocument)
      return element.contentDocument;
  else
      return null;
},
$: function(element, frameElement) { 
  element = $(element);
  var frameDocument = element.document();
  if (arguments.length > 2) {
      for (var i = 1, frameElements = [], length = arguments.length; i < length; i++)
          frameElements.push(element.$(arguments[i]));
      return frameElements;
  }
  if (Object.isString(frameElement))
      frameElement = frameDocument.getElementById(frameElement);
  return frameElement || element;
}
});