public void addChild(Element childElement){
  setChildParent(childElement);
  children.add(childElement);
}

public void addChild ( Element childElement ) { setChildParent ( childElement ) ; children . add ( childElement ) ; }
adds the specified element as a child to this element . if the specified element was found to be unsupported ( i . e . it ' s id is tag_unsupported , it is not added .
