code: public boolean addAll(Collection<T> coll) {
  	boolean newData = false;
  	for(T elem : coll) {
  	    if(set.add(elem)) {
  		newData = true;
  	    }
  	}
  	return newData;
      }
docs: Adds all elements of collection <code>coll</code> to
  <code>this</code> set.  Returns <code>true</code> iff we added
  at least one new element to this non-iterable set.