code: public void setComparator(int index, Comparator<T> comparator) {
  		if (comparator instanceof InvertibleComparator) {
  			this.comparators.set(index, (InvertibleComparator<T>) comparator);
  		}
  		else {
  			this.comparators.set(index, new InvertibleComparator<T>(comparator));
  		}
  	}
docs: Replace the Comparator at the given index.
  <p>The Comparator will default to ascending sort order,
  unless it is a InvertibleComparator.
  @param index the index of the Comparator to replace
  @param comparator the Comparator to place at the given index
  @see InvertibleComparator