Output enter_0 =
      ops::internal::Enter(root.WithOpName("enter_0"), a, "frame_0");
  Output exit_0 = ops::internal::Exit(root.WithOpName("exit_0"), enter_0);
  Output enter_1 =
      ops::internal::Enter(root.WithOpName("enter_1"), a, "frame_1");
  Output exit_1 = ops::internal::Exit(root.WithOpName("exit_1"), enter_1);
  Output b = ops::Add(root.WithOpName("b"), a, exit_1);

  auto enter_0 = ops::internal::Enter(root.WithOpName("enter_a"), a, "frame");
  auto exit_0 = ops::internal::Exit(root.WithOpName("exit_a"), enter_0);
  auto tanh = ops::Tanh(root.WithOpName("tanh"), exit_0);
  auto enter_1 =
      ops::internal::Enter(root.WithOpName("enter_1"), tanh, "frame");
  auto exit_1 = ops::internal::Exit(root.WithOpName("exit_1"), enter_1);

      }
    };
  }

  /** Enters this monitor. Blocks indefinitely. */
  public void enter() {
    lock.lock();
  }

  /**
   * Enters this monitor. Blocks at most the given time.
   *
   * @return whether the monitor was entered
   * @since 28.0
   */
  public boolean enter(Duration time) {
    return enter(toNanosSaturated(time), TimeUnit.NANOSECONDS);
  }

  /**

    this.lock = new ReentrantLock(fair);
  }

  /** Enters this monitor. Blocks indefinitely. */
  public void enter() {
    lock.lock();
  }

  /**
   * Enters this monitor. Blocks at most the given time.
   *
   * @return whether the monitor was entered
   */
  @SuppressWarnings("GoodTime") // should accept a java.time.Duration
  public boolean enter(long time, TimeUnit unit) {

    TestGuard guard = new TestGuard(true);
    thread1.callAndAssertReturns(true, enterIf(), guard);
    thread2.callAndAssertBlocks(enter());
  }

  public final void testEnterIf_initiallyFalse() throws Exception {
    TestGuard guard = new TestGuard(false);
    thread1.callAndAssertReturns(false, enterIf(), guard);
    thread2.callAndAssertReturns(enter());
  }

  public final void testEnterIf_alreadyOccupied() throws Exception {

    TestGuard guard = new TestGuard(true);
    thread1.callAndAssertReturns(true, enterIf(), guard);
    thread2.callAndAssertBlocks(enter());
  }

  public final void testEnterIf_initiallyFalse() throws Exception {
    TestGuard guard = new TestGuard(false);
    thread1.callAndAssertReturns(false, enterIf(), guard);
    thread2.callAndAssertReturns(enter());
  }

  public final void testEnterIf_alreadyOccupied() throws Exception {

    auto enter =
        ops::internal::Enter(scope.WithOpName("while/Enter"), source, "aloop");
    // Add an unused Enter node. These should be ignored.
    auto enter2 =
        ops::internal::Enter(scope.WithOpName("while/Enter2"), source, "aloop");
    auto merge = ops::Merge(scope.WithOpName("while/Merge"),
                            std::initializer_list<Input>{enter, dummy});
    auto ten = ops::Const<int32>(

   */
  @CanIgnoreReturnValue
  @Override
  public boolean offer(E e) {
    if (e == null) throw new NullPointerException();
    final Monitor monitor = this.monitor;
    if (monitor.enterIf(notFull)) {
      try {
        insert(e);
        return true;
      } finally {
        monitor.leave();
      }
    } else {
      return false;
    }
  }

  /**

   */
  @CanIgnoreReturnValue
  @Override
  public boolean offer(E e) {
    if (e == null) throw new NullPointerException();
    final Monitor monitor = this.monitor;
    if (monitor.enterIf(notFull)) {
      try {
        insert(e);
        return true;
      } finally {
        monitor.leave();
      }
    } else {
      return false;
    }
  }

  /**

 * therefore every method of the listener will be called at most once. N.B. The {@link State#FAILED}
 * and {@link State#TERMINATED} states are terminal states, once a service enters either of these
 * states it cannot ever leave them.
 *
 * <p>Implementors of this interface are strongly encouraged to extend one of the abstract classes