code: public void addComparator(Comparator<T> comparator, boolean ascending) {
  		this.comparators.add(new InvertibleComparator<T>(comparator, ascending));
  	}
docs: Add a Comparator to the end of the chain using the provided sort order.
  @param comparator the Comparator to add to the end of the chain
  @param ascending the sort order: ascending (true) or descending (false)