code: private Range<K> coalescedRange(Range<K> range, V value) {
      Range<K> coalescedRange = range;
      Entry<Cut<K>, RangeMapEntry<K, V>> lowerEntry =
          entriesByLowerBound.lowerEntry(range.lowerBound);
      coalescedRange = coalesce(coalescedRange, value, lowerEntry);
  
      Entry<Cut<K>, RangeMapEntry<K, V>> higherEntry =
          entriesByLowerBound.floorEntry(range.upperBound);
      coalescedRange = coalesce(coalescedRange, value, higherEntry);
  
      return coalescedRange;
    }
docs: Computes the coalesced range for the given range+value - does not mutate the map.