code: private void addEmptyElements() {
  		for (Node node : nodes)
  			if (helper.isEmpty(node))
  				result.add(node);
  	}
docs: Add {@code :empty} elements.
  
  @see <a href="http://www.w3.org/TR/css3-selectors/#empty-pseudo"><code>:empty</code> pseudo-class</a>