ImmutableSet<Integer> elements = ImmutableSet.of(1, 2, 3, 4);
    Set<Set<Integer>> forward = powerSet(elements);
    Set<Set<Integer>> reverse = powerSet(ImmutableSet.copyOf(elements.asList().reverse()));
    new EqualsTester().addEqualityGroup(forward, reverse).testEquals();
  }

  /**
   * Test that a hash code miscomputed by "input.hashCode() * tooFarValue / 2" is correct under our

    MapDifference<Integer, String> same = Maps.difference(left, right);
    MapDifference<Integer, String> reverse = Maps.difference(right, left);
    MapDifference<Integer, String> diff2 = Maps.difference(left, right2);

    new EqualsTester()
        .addEqualityGroup(original, same)
        .addEqualityGroup(reverse)
        .addEqualityGroup(diff2)
        .testEquals();
  }

    MapDifference<Integer, String> same = Maps.difference(left, right);
    MapDifference<Integer, String> reverse = Maps.difference(right, left);
    MapDifference<Integer, String> diff2 = Maps.difference(left, right2);

    new EqualsTester()
        .addEqualityGroup(original, same)
        .addEqualityGroup(reverse)
        .addEqualityGroup(diff2)
        .testEquals();
  }

  }

  /**
   * Returns a builder that creates immutable sorted maps whose keys are ordered by the reverse of
   * their natural ordering.
   */
  public static <K extends Comparable<?>, V> Builder<K, V> reverseOrder() {
    return new Builder<>(Ordering.<K>natural().reverse());
  }

  /**
   * A builder for creating immutable sorted map instances, especially {@code public static final}

      if (forwardComparator == null) {
        return (Comparator) Ordering.natural().reverse();
      } else {
        return reverse(forwardComparator);
      }
    }

    // If we inline this, we get a javac error.
    private static <T extends @Nullable Object> Ordering<T> reverse(Comparator<T> forward) {
      return Ordering.from(forward).reverse();
    }

    @Override
    @ParametricNullness

  }

  /**
   * Returns a builder that creates immutable sorted maps whose keys are ordered by the reverse of
   * their natural ordering.
   */
  public static <K extends Comparable<?>, V> Builder<K, V> reverseOrder() {
    return new Builder<>(Ordering.<K>natural().reverse());
  }

  /**
   * A builder for creating immutable sorted map instances, especially {@code public static final}

   * Returns the set of interfaces and classes that this type is or is a subtype of. The returned
   * types are parameterized with proper type arguments.
   *
   * <p>Subtypes are always listed before supertypes. But the reverse is not true. A type isn't
   * necessarily a subtype of all the types following. Order between types without subtype
   * relationship is arbitrary and not guaranteed.
   *

  /**
   * Returns the index of the last matching BMP character in a character sequence, or {@code -1} if
   * no matching character is present.
   *
   * <p>The default implementation iterates over the sequence in reverse order calling {@link
   * #matches} for each character.
   *
   * @param sequence the character sequence to examine from the end
   * @return an index, or {@code -1} if no character matches
   */

							if err != nil {
								cancel()
								return
							}

							// Note: entry.fileInfoVersions returns versions sorted in reverse chronological order based on ModTime
							if opts.VersionsSort == WalkVersionsSortAsc {
								versionsSorter(fivs.Versions).reverse()
							}

							for _, version := range fivs.Versions {
								if opts.Filter != nil {
									if opts.Filter(version) {

  /**
   * Returns the index of the last matching BMP character in a character sequence, or {@code -1} if
   * no matching character is present.
   *
   * <p>The default implementation iterates over the sequence in reverse order calling {@link
   * #matches} for each character.
   *
   * @param sequence the character sequence to examine from the end
   * @return an index, or {@code -1} if no character matches
   */