code: public static SimpleCheckBox wrap(Element element) {
          // Assert that the element is attached.
          assert Document.get().getBody().isOrHasChild(element);
  
          SimpleCheckBox checkBox = new SimpleCheckBox(InputElement.as(element));
  
          // Mark it attached and remember it for cleanup.
          checkBox.onAttach();
          RootPanel.detachOnWindowClose(checkBox);
  
          return checkBox;
      }
docs: Creates a SimpleCheckBox widget that wraps an existing &lt;input
  type='checkbox'&gt; element.
  
  This element must already be attached to the document. If the element is
  removed from the document, you must call
  {@link RootPanel#detachNow(Widget)}.
  
  @param element
  the element to be wrapped