}

    @Override
    public V remove(final Object key) {
        final Entry<K, V> e = removeMap(key);
        if (e != null) {
            final V value = e.value;
            removeList(entryIndexOf(e));
            e.clear();
            return value;
        }
        return null;
    }

    /**
     * Removes the entry at the specified index.
     *
     * @param index

     */
    public E removeFirst() {
        if (isEmpty()) {
            throw new NoSuchElementException();
        }
        final E first = header.next.element;
        header.next.remove();
        return first;
    }

    /**
     * Removes the last element.
     *
     * @return the last element
     */
    public E removeLast() {
        if (isEmpty()) {

 * defined as the <i>least</i> element in the queue according to the queue's comparator. But unlike
 * a regular priority queue, the methods {@link #peekLast}, {@link #pollLast} and {@link
 * #removeLast} are also provided, to act on the <i>greatest</i> element in the queue instead.
 *
 * <p>A min-max priority queue can be configured with a maximum size. If so, each time the size of

 * defined as the <i>least</i> element in the queue according to the queue's comparator. But unlike
 * a regular priority queue, the methods {@link #peekLast}, {@link #pollLast} and {@link
 * #removeLast} are also provided, to act on the <i>greatest</i> element in the queue instead.
 *
 * <p>A min-max priority queue can be configured with a maximum size. If so, each time the size of

    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;

        }

        @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();
        }

             */
            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