code: @Beta
    @GwtIncompatible // NavigableSet
    public static <K extends Comparable<? super K>> NavigableSet<K> subSet(
        NavigableSet<K> set, Range<K> range) {
      if (set.comparator() != null
          && set.comparator() != Ordering.natural()
          && range.hasLowerBound()
          && range.hasUpperBound()) {
        checkArgument(
            set.comparator().compare(range.lowerEndpoint(), range.upperEndpoint()) <= 0,
            "set is using a custom comparator which is inconsistent with the natural ordering.");
      }
      if (range.hasLowerBound() && range.hasUpperBound()) {
        return set.subSet(
            range.lowerEndpoint(),
            range.lowerBoundType() == BoundType.CLOSED,
            range.upperEndpoint(),
            range.upperBoundType() == BoundType.CLOSED);
      } else if (range.hasLowerBound()) {
        return set.tailSet(range.lowerEndpoint(), range.lowerBoundType() == BoundType.CLOSED);
      } else if (range.hasUpperBound()) {
        return set.headSet(range.upperEndpoint(), range.upperBoundType() == BoundType.CLOSED);
      }
      return checkNotNull(set);
    }
docs: Returns a view of the portion of {@code set} whose elements are contained by {@code range}.
  
  <p>This method delegates to the appropriate methods of {@link NavigableSet} (namely {@link
  NavigableSet#subSet(Object, boolean, Object, boolean) subSet()}, {@link
  NavigableSet#tailSet(Object, boolean) tailSet()}, and {@link NavigableSet#headSet(Object,
  boolean) headSet()}) to actually construct the view. Consult these methods for a full
  description of the returned view's behavior.
  
  <p><b>Warning:</b> {@code Range}s always represent a range of values using the values' natural
  ordering. {@code NavigableSet} on the other hand can specify a custom ordering via a {@link
  Comparator}, which can violate the natural ordering. Using this method (or in general using
  {@code Range}) with unnaturally-ordered sets can lead to unexpected and undefined behavior.
  
  @since 20.0