code: public boolean unUnified(E e) {
  	Node<E> node = elmap.get(e);
  	if(node == null) {
  	    // never been the argument of a call to union -> true
  	    return true;
  	}
  	// even if e was sent to union in the past, maybe it was
  	// unified only with equal elements; the following tests
  	// check this quickly
  	if(node.parent != node) {
  	    // already have a parent, so cannot be unUnified -> false
  	    return false;
  	}
  	// node is a root! last chance is that it's only a root of itself!
  	return node.nbElems == 1;
      }
docs: Returns true if the element <code>e</code> has not been
  unified yet with any DIFFERENT element.  Complexity: O(1).