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;
      N previousNode = prev == null ? null : prev.node;

    private final Deque<Runnable> tasks = new ArrayDeque<>();

    @Override
    public void execute(Runnable task) {
      tasks.add(task);
    }

    private void runNext() {
      tasks.removeFirst().run();
    }
  }

  public void testAsyncReload() throws Exception {
    AtomicInteger loadCount = new AtomicInteger();
    AtomicInteger reloadCount = new AtomicInteger();

        return delegate().offerLast(e);
      }
    }

    @Override
    public E removeFirst() {
      synchronized (mutex) {
        return delegate().removeFirst();
      }
    }

    @Override
    public E removeLast() {
      synchronized (mutex) {
        return delegate().removeLast();
      }
    }

    @Override
    public @Nullable E pollFirst() {

        return delegate().offerLast(e);
      }
    }

    @Override
    public E removeFirst() {
      synchronized (mutex) {
        return delegate().removeFirst();
      }
    }

    @Override
    public E removeLast() {
      synchronized (mutex) {
        return delegate().removeLast();
      }
    }

    @Override
    public @Nullable E pollFirst() {

        }

        @Override
        public ModelInterpolationException run() {
            while (!interpolationTargets.isEmpty()) {
                Object obj = interpolationTargets.removeFirst();

                try {
                    traverseObjectWithParents(obj.getClass(), obj);
                } catch (ModelInterpolationException e) {
                    return e;
                }

        }

        @Override
        void onEndHtmlElement(String name) {
            if (!tagStack.isEmpty() && tagStack.getFirst().equals(name)) {
                tagStack.removeFirst();
                handlerStack.removeFirst().onEndElement(name);
            }
        }

        @Override
        void onStartJavadocTag(String name) {
            tagValue = new StringBuilder();
        }

  override fun clean(
    chain: List<Certificate>,
    hostname: String,
  ): List<Certificate> {
    val queue: Deque<Certificate> = ArrayDeque(chain)
    val result = mutableListOf<Certificate>()
    result.add(queue.removeFirst())
    var foundTrustedCertificate = false

    followIssuerChain@
    for (c in 0 until MAX_SIGNERS) {
      val toVerify = result[result.size - 1] as X509Certificate

             */
            requireNonNull(element);
            if (visited.add(element)) {
              return element;
            }
          }
          horizon.removeFirst();
          return null;
        }
      };
    }

    static <N> Traversal<N> inTree(SuccessorsFunction<N> tree) {
      return new Traversal<N>(tree) {
        @Override

            this.problems = problems;
        }

        public Object run() {
            while (!interpolationTargets.isEmpty()) {
                Object obj = interpolationTargets.removeFirst();

                traverseObjectWithParents(obj.getClass(), obj);
            }
            return null;
        }

        private String interpolate(String value) {

    val pooled1 = planReusePooledConnection()
    if (pooled1 != null) return pooled1

    // Attempt a deferred plan before new routes.
    if (deferredPlans.isNotEmpty()) return deferredPlans.removeFirst()

    // Do blocking calls to plan a route for a new connection.
    val connect = planConnect()

    // Now that we have a set of IP addresses, make another attempt at getting a connection from