return new StandardElementSet();
    }

    @Override
    public Entry<E> firstEntry() {
      return standardFirstEntry();
    }

    @Override
    public Entry<E> lastEntry() {
      return standardLastEntry();
    }

    @Override
    public Entry<E> pollFirstEntry() {
      return standardPollFirstEntry();
    }

    @Override
    public Entry<E> pollLastEntry() {
      return standardPollLastEntry();

      return new StandardElementSet();
    }

    @Override
    public Entry<E> firstEntry() {
      return standardFirstEntry();
    }

    @Override
    public Entry<E> lastEntry() {
      return standardLastEntry();
    }

    @Override
    public Entry<E> pollFirstEntry() {
      return standardPollFirstEntry();
    }

    @Override
    public Entry<E> pollLastEntry() {
      return standardPollLastEntry();

   *
   * <p>If you override {@link #descendingMultiset} or {@link #entrySet()}, you may wish to override
   * {@link #firstEntry()} to forward to this implementation.
   */
  @CheckForNull
  protected Entry<E> standardLastEntry() {
    Iterator<Entry<E>> entryIterator = descendingMultiset().entrySet().iterator();
    if (!entryIterator.hasNext()) {
      return null;
    }
    Entry<E> entry = entryIterator.next();

   *
   * <p>If you override {@link #descendingMultiset} or {@link #entrySet()}, you may wish to override
   * {@link #firstEntry()} to forward to this implementation.
   */
  @CheckForNull
  protected Entry<E> standardLastEntry() {
    Iterator<Entry<E>> entryIterator = descendingMultiset().entrySet().iterator();
    if (!entryIterator.hasNext()) {
      return null;
    }
    Entry<E> entry = entryIterator.next();

   *
   * <p>If you override {@link #descendingMultiset} or {@link #entrySet()}, you may wish to override
   * {@link #firstEntry()} to forward to this implementation.
   */
  @CheckForNull
  protected Entry<E> standardLastEntry() {
    Iterator<Entry<E>> entryIterator = descendingMultiset().entrySet().iterator();
    if (!entryIterator.hasNext()) {
      return null;
    }
    Entry<E> entry = entryIterator.next();

   * #entrySet} of {@link #descendingMap}. If you override {@code descendingMap}, you may wish to
   * override {@code lastEntry} to forward to this implementation.
   */
  @CheckForNull
  protected Entry<K, V> standardLastEntry() {
    return Iterables.<@Nullable Entry<K, V>>getFirst(descendingMap().entrySet(), null);
  }

  /**
   * A sensible definition of {@link #lastKey} in terms of {@code lastEntry}. If you override {@code

   * #entrySet} of {@link #descendingMap}. If you override {@code descendingMap}, you may wish to
   * override {@code lastEntry} to forward to this implementation.
   */
  @CheckForNull
  protected Entry<K, V> standardLastEntry() {
    return Iterables.<@Nullable Entry<K, V>>getFirst(descendingMap().entrySet(), null);
  }

  /**
   * A sensible definition of {@link #lastKey} in terms of {@code lastEntry}. If you override {@code