public Element addElementToRegistry(Element element){
  if (element == null)   return (this);
  int hc=element.hashCode();
  String s=Integer.toString(hc);
  addElementToRegistry(s,element);
  return (this);
}

public Element addElementToRegistry ( Element element ) { if ( element == null ) return ( this ) ; int hc = element . hashCode ( ) ; String s = Integer . toString ( hc ) ; addElementToRegistry ( s , element ) ; return ( this ) ; }
registers an element in the head element list
