*/
    private final Range<Cut<C>> upperBoundWindow;

    RangesByUpperBound(NavigableMap<Cut<C>, Range<C>> rangesByLowerBound) {
      this.rangesByLowerBound = rangesByLowerBound;
      this.upperBoundWindow = Range.all();
    }

    private RangesByUpperBound(
        NavigableMap<Cut<C>, Range<C>> rangesByLowerBound, Range<Cut<C>> upperBoundWindow) {