return new Builder<>(Ordering.<K>natural().reverse());
  }

  /**
   * A builder for creating immutable sorted map instances, especially {@code public static final}
   * maps ("constant maps"). Example:
   *
   * <pre>{@code
   * static final ImmutableSortedMap<Integer, String> INT_TO_WORD =
   *     new ImmutableSortedMap.Builder<Integer, String>(Ordering.natural())
   *         .put(1, "one")

    try {
      Maps.toMap((Iterable<String>) strings, Functions.constant("foo"));
      fail();
    } catch (NullPointerException expected) {
    }
  }

  public void testToMapWithNullValues() {
    Iterable<String> strings = ImmutableList.of("one", "two", "three");
    try {
      Maps.toMap(strings, Functions.constant(null));
      fail();
    } catch (NullPointerException expected) {
    }
  }

    try {
      Maps.toMap((Iterable<String>) strings, Functions.constant("foo"));
      fail();
    } catch (NullPointerException expected) {
    }
  }

  public void testToMapWithNullValues() {
    Iterable<String> strings = ImmutableList.of("one", "two", "three");
    try {
      Maps.toMap(strings, Functions.constant(null));
      fail();
    } catch (NullPointerException expected) {
    }
  }

    return new Builder<>(Ordering.<K>natural().reverse());
  }

  /**
   * A builder for creating immutable sorted map instances, especially {@code public static final}
   * maps ("constant maps"). Example:
   *
   * <pre>{@code
   * static final ImmutableSortedMap<Integer, String> INT_TO_WORD =
   *     new ImmutableSortedMap.Builder<Integer, String>(Ordering.natural())
   *         .put(1, "one")

   *                            8
   */

  // Constant matcher factory methods

  /**
   * Matches any character.
   *
   * @since 19.0 (since 1.0 as constant {@code ANY})
   */
  public static CharMatcher any() {
    return Any.INSTANCE;
  }

  /**
   * Matches no characters.
   *
   * @since 19.0 (since 1.0 as constant {@code NONE})
   */
  public static CharMatcher none() {

   *                            8
   */

  // Constant matcher factory methods

  /**
   * Matches any character.
   *
   * @since 19.0 (since 1.0 as constant {@code ANY})
   */
  public static CharMatcher any() {
    return Any.INSTANCE;
  }

  /**
   * Matches no characters.
   *
   * @since 19.0 (since 1.0 as constant {@code NONE})
   */
  public static CharMatcher none() {

   * is merely copied. Only as the power set is iterated are the individual subsets created, and
   * these subsets themselves occupy only a small constant amount of memory.
   *
   * @param set the set of elements to construct a power set from
   * @return the power set, as an immutable set of immutable sets