* Returns the option followed by a string representation of the given path elements.
     * The path elements are separated by an option-specific or platform-specific separator.
     * If the given {@code paths} argument contains no element, then this method returns an empty string.
     *
     * <h4>Examples</h4>
     * If {@code paths} is a list containing two elements, {@code dir/path1} and {@code dir/path2}, then:
     *
     * <ul>

  /**
   * A collector that converts a stream of zero or one elements to an {@code Optional}.
   *
   * @throws IllegalArgumentException if the stream consists of two or more elements.
   * @throws NullPointerException if any element in the stream is {@code null}.
   * @return {@code Optional.of(onlyElement)} if the stream has exactly one element (must not be
   *     {@code null}) and returns {@code Optional.empty()} if it has none.

    Iterator<E> iterator = collection.iterator();
    Object element = iterator.next();
    // If it's an Entry, it may become invalid once it's removed from the Map. Copy it.
    if (element instanceof Entry) {
      Entry<?, ?> entry = (Entry<?, ?>) element;
      element = mapEntry(entry.getKey(), entry.getValue());
    }
    assertTrue(collection.contains(element)); // sanity check
    iterator.remove();

    implements TestSortedSetGenerator<String> {

  @Override
  public SortedSet<String> create(Object... elements) {
    return (SortedSet<String>) super.create(elements);
  }

  @Override
  protected abstract SortedSet<String> create(String[] elements);

  /** Sorts the elements by their natural ordering. */
  /*
   * While the current implementation returns `this`, that's not something we mean to guarantee.

 * <i>lesser</i> are considered to refer to the comparator on the elements, and the terms
 * <i>first</i> and <i>last</i> are considered to refer to the elements' ordering in a list.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
final class SortedLists {
  private SortedLists() {}

  /**
   * A specification for which index to return if the list contains at least one element that
   * compares as equal to the key.
   */

  protected <E extends Comparable<? super E>> Set<E> copyOf(E[] elements) {
    return ImmutableSet.copyOf(elements);
  }

  @Override
  protected <E extends Comparable<? super E>> Set<E> copyOf(Collection<? extends E> elements) {
    return ImmutableSet.copyOf(elements);
  }

  @Override
  protected <E extends Comparable<? super E>> Set<E> copyOf(Iterable<? extends E> elements) {
    return ImmutableSet.copyOf(elements);
  }

    return new Enums();
  }

  @Override
  public Multiset<AnEnum> create(Object... elements) {
    AnEnum[] array = new AnEnum[elements.length];
    int i = 0;
    for (Object e : elements) {
      array[i++] = (AnEnum) e;
    }
    return create(array);
  }

  protected abstract Multiset<AnEnum> create(AnEnum[] elements);

  @Override
  public AnEnum[] createArray(int length) {
    return new AnEnum[length];

        .onClose(streamB::close);
  }

  /**
   * Invokes {@code consumer} once for each pair of <i>corresponding</i> elements in {@code streamA}
   * and {@code streamB}. If one stream is longer than the other, the extra elements are silently
   * ignored. Elements passed to the consumer are guaranteed to come from the same position in their
   * respective source streams. For example:
   *
   * {@snippet :

    return new LexicographicalOrdering<S>(checkNotNull(comparator));
  }

  /**
   * Returns {@code true} if each element in {@code iterable} after the first is greater than or
   * equal to the element that preceded it, according to the specified comparator. Note that this is
   * always true when the iterable has fewer than two elements.
   */
  public static <T extends @Nullable Object> boolean isInOrder(

   *       href="https://github.com/google/guava/wiki/GraphsExplained#graph-elements-nodes-and-edges">
   *       graph elements</a> for details)
   * </ul>
   *
   * @throws IllegalArgumentException if {@code node} is not an element of this graph
   */
  Iterable<? extends N> predecessors(N node);