code: @Override
  	public ExtendedSet<T> tailSet(T fromElement) {
  		if (elements instanceof SortedSet<?>) {
  			GenericExtendedSet<T> c = empty();
  			c.elements = ((SortedSet<T>) elements).tailSet(fromElement);
  			return c;
  		}
  		return super.headSet(fromElement);
  	}
docs: {@inheritDoc}