code: public Comparator<S> comparator() {
          if (mChunkMatcher == null) {
              return mChunkSorter;
          }
          return new Comparator<S>() {
              public int compare(S a, S b) {
                  int result = mChunkMatcher.compare(a, b);
                  if (result == 0) {
                      result = mChunkSorter.compare(a, b);
                  }
                  return result;
              }
          };
      }
docs: Returns a comparator representing the effective sort order of this cursor.