return !TreeRangeSet.this.contains(value);
    }

    @Override
    public RangeSet<C> complement() {
      return TreeRangeSet.this;
    }
  }

  private static final class SubRangeSetRangesByLowerBound<C extends Comparable<?>>
      extends AbstractNavigableMap<Cut<C>, Range<C>> {
    /**
     * lowerBoundWindow is the headMap/subMap/tailMap view; it only restricts the keys, and does not
     * affect the values.