public void testRemove() throws Exception {
        list.addLast(null);
        list.addLast("1");
        list.addLast("2");
        assertThat(list.remove("3"), is(not(true)));
        assertThat(list.remove("1"), is(true));
        assertThat(list.remove(null), is(true));
        list.clear();
        list.addLast("1");
        list.addLast("2");
        list.addLast("3");
        list.remove(1);

      this.stack = new ArrayDeque<>();
      stack.addLast(expand(root));
    }

    @Override
    protected @Nullable T computeNext() {
      while (!stack.isEmpty()) {
        PostOrderNode<T> top = stack.getLast();
        if (top.childIterator.hasNext()) {
          T child = top.childIterator.next();
          stack.addLast(expand(child));
        } else {
          stack.removeLast();

    @Override
    public void addFirst(E e) {
      assertTrue(Thread.holdsLock(mutex));
      delegate.addFirst(e);
    }

    @Override
    public void addLast(E e) {
      assertTrue(Thread.holdsLock(mutex));
      delegate.addLast(e);
    }

    @Override
    public boolean offerFirst(E e) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.offerFirst(e);
    }

      this.stack = new ArrayDeque<>();
      stack.addLast(expand(root));
    }

    @Override
    protected @Nullable T computeNext() {
      while (!stack.isEmpty()) {
        PostOrderNode<T> top = stack.getLast();
        if (top.childIterator.hasNext()) {
          T child = top.childIterator.next();
          stack.addLast(expand(child));
        } else {
          stack.removeLast();

  @Override
  protected abstract Deque<E> delegate();

  @Override
  public void addFirst(@ParametricNullness E e) {
    delegate().addFirst(e);
  }

  @Override
  public void addLast(@ParametricNullness E e) {
    delegate().addLast(e);
  }

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

  @Override
  @ParametricNullness
  public E getFirst() {

        header.previous = header;
        for (int i = 0; i < size; i++) {
            addLast((E) s.readObject());
        }
    }

    @Override
    public Object clone() {
        final SLinkedList<E> copy = new SLinkedList<>();
        for (Entry e = header.next; e != header; e = e.next) {
            copy.addLast(e.element);
        }
        return copy;
    }

    /**

    @Override
    public void addFirst(E e) {
      assertTrue(Thread.holdsLock(mutex));
      delegate.addFirst(e);
    }

    @Override
    public void addLast(E e) {
      assertTrue(Thread.holdsLock(mutex));
      delegate.addLast(e);
    }

    @Override
    public boolean offerFirst(E e) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.offerFirst(e);
    }

     *            A disposable resource. Must not be {@literal null}.
     */
    public static synchronized void add(final Disposable disposable) {
        assertArgumentNotNull("disposable", disposable);
        disposables.addLast(disposable);
    }

    /**
     * Registers a disposable resource at the beginning.
     * <p>

        if (state.set) {
          return java.util.Optional.of(state.get());
        }
        // fall back to the last split
        continue;
      }
      splits.addLast(prefix);
      splits.addLast(spliterator);
    }
    return java.util.Optional.empty();
  }

  /**
   * Returns the last element of the specified stream, or {@link OptionalInt#empty} if the stream is
   * empty.
   *

    Deque<NodeAndRemainingSuccessors<N>> stack = new ArrayDeque<>();
    stack.addLast(new NodeAndRemainingSuccessors<>(startNode));

    while (!stack.isEmpty()) {
      // To peek at the top two items, we need to temporarily remove one.
      NodeAndRemainingSuccessors<N> top = stack.removeLast();
      NodeAndRemainingSuccessors<N> prev = stack.peekLast();
      stack.addLast(top);

      N node = top.node;