@Override
 public Object clone( ){// Clone an IntTreeBag object.
     IntTreeBag answer = null;
   
     try{
         answer = (IntTreeBag) super.clone();
     }catch(CloneNotSupportedException e){
         System.out.println(e.toString());
     }
     answer.root = IntBTNode.treeCopy(root);
    return answer; 
 }