*
   * @param iterable the iterable to copy
   * @return a newly-allocated array into which all the elements of the iterable have been copied
   */
  static @Nullable Object[] toArray(Iterable<?> iterable) {
    return castOrCopyToCollection(iterable).toArray();
  }

  /**
   * Converts an iterable into a collection. If the iterable is already a collection, it is

  // Ordering<Iterable<String>> o =
  //     Ordering.<String>natural().lexicographical();
  public <S extends T> Ordering<Iterable<S>> lexicographical() {
    /*
     * Note that technically the returned ordering should be capable of
     * handling not just {@code Iterable<S>} instances, but also any {@code
     * Iterable<? extends S>}. However, the need for this comes up so rarely

    Iterable<String> iterable = asList("a", "b");
    Iterator<String> cycle = Iterators.cycle(iterable);
    cycle.next();
    try {
      cycle.remove();
      fail("no exception thrown");
    } catch (UnsupportedOperationException expected) {
    }
  }

  public void testCycleRemoveAfterHasNext() {
    Iterable<String> iterable = Lists.newArrayList("a");

   * always true when the iterable has fewer than two elements.
   */
  public static <T extends @Nullable Object> boolean isInOrder(
      Iterable<? extends T> iterable, Comparator<T> comparator) {
    checkNotNull(comparator);
    Iterator<? extends T> it = iterable.iterator();
    if (it.hasNext()) {
      T prev = it.next();
      while (it.hasNext()) {
        T next = it.next();
        if (comparator.compare(prev, next) > 0) {

   * Returns an iterator that cycles indefinitely over the elements of {@code iterable}.
   *
   * <p>The returned iterator supports {@code remove()} if the provided iterator does. After {@code
   * remove()} is called, subsequent cycles omit the removed element, which is no longer in {@code
   * iterable}. The iterator's {@code hasNext()} method returns {@code true} until {@code iterable}
   * is empty.
   *

   * accepts non-{@code Collection} iterables and empty iterables.
   */
  public static <E extends Enum<E>> EnumSet<E> newEnumSet(
      Iterable<E> iterable, Class<E> elementType) {
    EnumSet<E> set = EnumSet.noneOf(elementType);
    Iterables.addAll(set, iterable);
    return set;
  }

  // HashSet

  /**

  private static final Iterable<Integer> SOME_ITERABLE = new SomeIterable();

  private static final class RemoveFirstFunction implements Function<String, String>, Serializable {
    @Override
    public String apply(String from) {
      return (from.length() == 0) ? from : from.substring(1);
    }
  }

  private static class SomeIterable implements Iterable<Integer>, Serializable {
    @Override

  private static final Iterable<Integer> SOME_ITERABLE = new SomeIterable();

  private static final class RemoveFirstFunction implements Function<String, String>, Serializable {
    @Override
    public String apply(String from) {
      return (from.length() == 0) ? from : from.substring(1);
    }
  }

  private static class SomeIterable implements Iterable<Integer>, Serializable {
    @Override

   * will be merged.
   *
   * @throws IllegalArgumentException if any ranges overlap or are empty
   * @since 21.0
   */
  public static <C extends Comparable<?>> ImmutableRangeSet<C> copyOf(Iterable<Range<C>> ranges) {
    return new ImmutableRangeSet.Builder<C>().addAll(ranges).build();
  }

  /**
   * Returns an {@code ImmutableRangeSet} representing the union of the specified ranges.
   *

     *
     * @param elements the {@code Iterable} to add to the {@code ImmutableList}
     * @return this {@code Builder} object
     * @throws NullPointerException if {@code elements} is null or contains a null element
     */
    @CanIgnoreReturnValue
    @Override
    public Builder<E> addAll(Iterable<? extends E> elements) {
      super.addAll(elements);
      return this;
    }