* powerSet(ImmutableSet.of(1, 2))} returns the set {@code {{}, {1}, {2}, {1, 2}}}.
   *
   * <p>Elements appear in these subsets in the same iteration order as they appeared in the input
   * set. The order in which these subsets appear in the outer set is undefined. Note that the power
   * set of the empty set is not the empty set, but a one-element set containing the empty set.
   *

  /**
   * Returns an immutable list containing the given elements, sorted according to their natural
   * order. The sorting algorithm used is stable, so elements that compare as equal will stay in the
   * order in which they appear in the input.
   *
   * <p>If your data has no duplicates, or you wish to deduplicate elements, use {@code
   * ImmutableSortedSet.copyOf(elements)}; if you want a {@code List} you can use its {@code
   * asList()} view.

   * calling the function on that value. The resulting multimap is created as an immutable snapshot.
   * In the returned multimap, keys appear in the order they are first encountered, and the values
   * corresponding to each key appear in the same order as they are encountered.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.collect(Collectors.groupingBy(keyFunction))}

   * calling the function on that value. The resulting multimap is created as an immutable snapshot.
   * In the returned multimap, keys appear in the order they are first encountered, and the values
   * corresponding to each key appear in the same order as they are encountered.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.collect(Collectors.groupingBy(keyFunction))}

      if (placeholderStart == -1) {
        break;
      }
      builder.append(template, templateStart, placeholderStart);
      builder.append(lenientToString(args[i++]));
      templateStart = placeholderStart + 2;
    }
    builder.append(template, templateStart, template.length());

    // if we run out of placeholders, append the extra args in square brackets
    if (i < args.length) {
      String prefix = " [";

  @Override
  Set<V> values();

  /**
   * Returns the inverse view of this bimap, which maps each of this bimap's values to its
   * associated key. The two bimaps are backed by the same data; any changes to one will appear in
   * the other.
   *
   * <p><b>Note:</b> There is no guaranteed correspondence between the iteration order of a bimap
   * and that of its inverse.
   *
   * @return the inverse view of this bimap
   */

  }

  @Override
  public int size() {
    return size;
  }

  // views

  /**
   * Returns an immutable set of the distinct keys in this multimap, in the same order as they
   * appear in this multimap.
   */
  @Override
  public ImmutableSet<K> keySet() {
    return map.keySet();
  }

  @Override
  Set<K> createKeySet() {
    throw new AssertionError("unreachable");
  }

  /**
   * Returns a {@code Collector} that accumulates the input elements into a new {@code
   * ImmutableSet}. Elements appear in the resulting set in the encounter order of the stream; if
   * the stream contains duplicates (according to {@link Object#equals(Object)}), only the first
   * duplicate in encounter order will appear in the result.
   *
   * @since 21.0
   */
  public static <E> Collector<E, ?, ImmutableSet<E>> toImmutableSet() {

  /**
   * Returns a {@link Collector} that accumulates elements into an {@code ImmutableBiMap} whose keys
   * and values are the result of applying the provided mapping functions to the input elements.
   * Entries appear in the result {@code ImmutableBiMap} in encounter order.
   *
   * <p>If the mapped keys or values contain duplicates (according to {@link

  }

  @Override
  public int hashCode() {
    return Sets.hashCodeImpl(this);
  }

  // This declaration is needed to make Set.iterator() and
  // ImmutableCollection.iterator() appear consistent to javac's type inference.
  @Override
  public abstract UnmodifiableIterator<E> iterator();

  abstract static class CachingAsList<E> extends ImmutableSet<E> {