*
   * <p>Some algorithms that operate on a {@code SuccessorsFunction} may produce undesired results
   * if the returned {@link Iterable} contains duplicate elements. Implementations of such
   * algorithms should document their behavior in the presence of duplicates.
   *
   * <p>The elements of the returned {@code Iterable} must each be:
   *
   * <ul>
   *   <li>Non-null

   * 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.
   *

  }

  /**
   * This Iterator claims to have more elements than the underlying iterable, but when you try to
   * fetch the extra elements, it throws an unchecked exception.
   */
  static class ThrowsAtEndIterator<E> implements Iterator<E> {
    Iterator<E> iterator;

    public ThrowsAtEndIterator(Iterable<E> iterable) {
      this.iterator = iterable.iterator();
    }

    @Override
    public boolean hasNext() {

     */
    @Nonnull
    @Override
    public String[] option(Iterable<? extends Path> paths) {
        return format(null, paths);
    }

    /**
     * Implementation shared with {@link Modular}.
     */
    final String[] format(String moduleName, Iterable<? extends Path> paths) {
        if (option == null) {

  /**
   * Find all the tester annotations declared on a tester class or method.
   *
   * @param classOrMethod a class or method whose tester annotations to find
   * @return an iterable sequence of tester annotations on the class
   */
  public static Iterable<Annotation> getTesterAnnotations(AnnotatedElement classOrMethod) {
    synchronized (annotationCache) {
      List<Annotation> annotations = annotationCache.get(classOrMethod);

 * implementation for the {@link #put} and {@link #getIfPresent} methods. {@link #getAllPresent} is
 * implemented in terms of {@link #getIfPresent}; {@link #putAll} is implemented in terms of {@link
 * #put}, {@link #invalidateAll(Iterable)} is implemented in terms of {@link #invalidate}. The
 * method {@link #cleanUp} is a no-op. All other methods throw an {@link
 * UnsupportedOperationException}.
 *
 * @author Charles Fry
 * @since 10.0
 */

    CountingIterable iterable = new CountingIterable();
    List<String> list = ImmutableList.copyOf(iterable);
    assertEquals(asList("a", "b", "a"), list);
  }

  public void testCopyOf_plainIterable_iteratesOnce() {
    CountingIterable iterable = new CountingIterable();
    ImmutableList<String> unused = ImmutableList.copyOf(iterable);
    assertEquals(1, iterable.count);
  }

    UNKNOWN_ORDER
  }

  @SuppressWarnings("unchecked") // TODO(cpovirk): Stop using arrays.
  AbstractIteratorTester(
      int steps,
      Iterable<E> elementsToInsertIterable,
      Iterable<? extends IteratorFeature> features,
      Iterable<E> expectedElements,
      KnownOrder knownOrder,
      int startIndex) {
    // periodically we should manually try (steps * 3 / 2) here; all tests but

    @Override
    public SampleElements<String> sampleValues() {
      return new SampleElements<>("january", "february", "march", "april", "may");
    }

    @Override
    public Collection<String> createCollection(Iterable<? extends String> values) {
      return Lists.newArrayList(values);
    }

    @Override
    public SampleElements<Entry<String, String>> samples() {
      return new SampleElements<>(

   * 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

  /**