assertTrue(Range.closed(3, 5).isConnected(Range.open(5, 6)));
    assertTrue(Range.closed(3, 5).isConnected(Range.closed(5, 6)));
    assertTrue(Range.closed(5, 6).isConnected(Range.closed(3, 5)));
    assertTrue(Range.closed(3, 5).isConnected(Range.openClosed(5, 5)));
    assertTrue(Range.open(3, 5).isConnected(Range.closed(5, 6)));
    assertTrue(Range.closed(3, 7).isConnected(Range.open(6, 8)));

    }

    @Override
    public void remove(Range<K> range) {
      if (range.isConnected(subRange)) {
        TreeRangeMap.this.remove(range.intersection(subRange));
      }
    }

    @Override
    public RangeMap<K, V> subRangeMap(Range<K> range) {
      if (!range.isConnected(subRange)) {
        return emptySubRangeMap();
      } else {

            NEXT_HIGHER);
    if (ceilingIndex < ranges.size()
        && ranges.get(ceilingIndex).isConnected(otherRange)
        && !ranges.get(ceilingIndex).intersection(otherRange).isEmpty()) {
      return true;
    }
    return ceilingIndex > 0
        && ranges.get(ceilingIndex - 1).isConnected(otherRange)
        && !ranges.get(ceilingIndex - 1).intersection(otherRange).isEmpty();
  }

  @Override

  private static <K extends Comparable, V> Range<K> coalesce(
      Range<K> range, V value, @CheckForNull Entry<Cut<K>, RangeMapEntry<K, V>> entry) {
    if (entry != null
        && entry.getValue().getKey().isConnected(range)
        && entry.getValue().getValue().equals(value)) {
      return range.span(entry.getValue().getKey());
    }
    return range;
  }

  @Override

      for (int i = 0; i < entries.size(); i++) {
        Range<K> range = entries.get(i).getKey();
        if (i > 0) {
          Range<K> prevRange = entries.get(i - 1).getKey();
          if (range.isConnected(prevRange) && !range.intersection(prevRange).isEmpty()) {
            throw new IllegalArgumentException(
                "Overlapping ranges: range " + prevRange + " overlaps with entry " + range);
          }
        }