}

  @Override
  public boolean containsAll(Collection<?> c) {
    return delegate.containsAll(c);
  }

  @Override
  public Iterator<E> descendingIterator() {
    return delegate.descendingIterator();
  }

  @Override
  public NavigableSet<E> descendingSet() {
    return new SafeTreeSet<>(delegate.descendingSet());
  }

  @Override
  public E first() {

  }

  @Override
  public UnmodifiableIterator<C> iterator() {
    return Iterators.emptyIterator();
  }

  @GwtIncompatible // NavigableSet
  @Override
  public UnmodifiableIterator<C> descendingIterator() {
    return Iterators.emptyIterator();
  }

  @Override
  boolean isPartialView() {
    return false;
  }

  @Override
  public boolean isEmpty() {
    return true;
  }

    }

    @Override
    public NavigableSet<E> descendingSet() {
      return new NavigableElementSet<>(multiset().descendingMultiset());
    }

    @Override
    public Iterator<E> descendingIterator() {
      return descendingSet().iterator();
    }

    @Override
    @CheckForNull
    public E pollFirst() {
      return getElementOrNull(multiset().pollFirstEntry());
    }

  }

  @Override
  public UnmodifiableIterator<C> iterator() {
    return Iterators.emptyIterator();
  }

  @GwtIncompatible // NavigableSet
  @Override
  public UnmodifiableIterator<C> descendingIterator() {
    return Iterators.emptyIterator();
  }

  @Override
  boolean isPartialView() {
    return false;
  }

  @Override
  public boolean isEmpty() {
    return true;
  }

    }

    @Override
    public NavigableSet<E> descendingSet() {
      return new NavigableElementSet<>(multiset().descendingMultiset());
    }

    @Override
    public Iterator<E> descendingIterator() {
      return descendingSet().iterator();
    }

    @Override
    @CheckForNull
    public E pollFirst() {
      return getElementOrNull(multiset().pollFirstEntry());
    }

        return equalsOrThrow(previous, last) ? null : domain.next(previous);
      }
    };
  }

  @GwtIncompatible // NavigableSet
  @Override
  public UnmodifiableIterator<C> descendingIterator() {
    return new AbstractSequentialIterator<C>(last()) {
      final C first = first();

      @Override
      @CheckForNull
      protected C computeNext(C previous) {

        return equalsOrThrow(previous, last) ? null : domain.next(previous);
      }
    };
  }

  @GwtIncompatible // NavigableSet
  @Override
  public UnmodifiableIterator<C> descendingIterator() {
    return new AbstractSequentialIterator<C>(last()) {
      final C first = first();

      @Override
      @CheckForNull
      protected C computeNext(C previous) {

  }

  @CollectionSize.Require(SEVERAL)
  public void testDescendingNavigation() {
    List<E> descending = new ArrayList<>();
    for (Iterator<E> i = navigableSet.descendingIterator(); i.hasNext(); ) {
      descending.add(i.next());
    }
    Collections.reverse(descending);
    assertEquals(values, descending);
  }

  public void testEmptySubSet() {

  }

  @Override
  public UnmodifiableIterator<E> iterator() {
    return elements.iterator();
  }

  @GwtIncompatible // NavigableSet
  @Override
  public UnmodifiableIterator<E> descendingIterator() {
    return elements.reverse().iterator();
  }

  @Override
  public Spliterator<E> spliterator() {
    return asList().spliterator();
  }

  @Override

  }

  @Override
  public UnmodifiableIterator<E> iterator() {
    return elements.iterator();
  }

  @GwtIncompatible // NavigableSet
  @Override
  public UnmodifiableIterator<E> descendingIterator() {
    return elements.reverse().iterator();
  }

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

  @Override
  public boolean contains(@CheckForNull Object o) {
    try {