return Iterators.pollNext(iterator());
  }

  @Override
  public @Nullable E pollLast() {
    return delegate().pollLast();
  }

  /**
   * A sensible definition of {@link #pollLast} in terms of the {@code descendingIterator} method.
   * If you override {@link #descendingIterator} you may wish to override {@link #pollLast} to
   * forward to this implementation.
   */
  protected @Nullable E standardPollLast() {

    return Iterators.pollNext(iterator());
  }

  @Override
  public @Nullable E pollLast() {
    return delegate().pollLast();
  }

  /**
   * A sensible definition of {@link #pollLast} in terms of the {@code descendingIterator} method.
   * If you override {@link #descendingIterator} you may wish to override {@link #pollLast} to
   * forward to this implementation.
   */
  protected @Nullable E standardPollLast() {

    return delegate().pollFirst(timeout, unit);
  }

  @Override
  public @Nullable E pollLast(long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().pollLast(timeout, unit);
  }

  @Override
  public void put(E e) throws InterruptedException {
    delegate().put(e);
  }

  @Override

  @Override
  public @Nullable E pollFirst() {
    return delegate().pollFirst();
  }

  @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
  @Override
  public @Nullable E pollLast() {
    return delegate().pollLast();
  }

  @CanIgnoreReturnValue
  @Override
  @ParametricNullness
  public E pop() {
    return delegate().pop();
  }

  @Override

    public @Nullable E pollFirst() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.pollFirst();
    }

    @Override
    public @Nullable E pollLast() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.pollLast();
    }

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

    @Override

    return delegate().pollFirst(timeout, unit);
  }

  @Override
  public @Nullable E pollLast(long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().pollLast(timeout, unit);
  }

  @Override
  public void put(E e) throws InterruptedException {
    delegate().put(e);
  }

  @Override

  @Override
  public @Nullable E pollFirst() {
    return delegate().pollFirst();
  }

  @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
  @Override
  public @Nullable E pollLast() {
    return delegate().pollLast();
  }

  @CanIgnoreReturnValue
  @Override
  @ParametricNullness
  public E pop() {
    return delegate().pop();
  }

  @Override

    return delegate.lower(checkValid(e));
  }

  @Override
  public @Nullable E pollFirst() {
    return delegate.pollFirst();
  }

  @Override
  public @Nullable E pollLast() {
    return delegate.pollLast();
  }

  @Override
  public boolean remove(Object object) {
    return delegate.remove(checkValid(object));
  }

  @Override
  public boolean removeAll(Collection<?> c) {

  public @Nullable E pollFirst(long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().pollFirst(timeout, unit);
  }

  @Override
  public @Nullable E pollLast(long timeout, TimeUnit unit) throws InterruptedException {
    return delegate().pollLast(timeout, unit);
  }

  @Override
  public void put(E e) throws InterruptedException {
    delegate().put(e);
  }

  @Override

    public @Nullable E pollFirst() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.pollFirst();
    }

    @Override
    public @Nullable E pollLast() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.pollLast();
    }

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

    @Override