code: public Object set(int index, Object element) {
  
          Node   setMe   = getInternal(index);
          Object oldData = setMe.data;
  
          setMe.data = element;
  
          return oldData;
      }
docs: Replaces the current element at <code>index/code> with
  <code>element</code>.
  @return The current element at <code>index</code>.