/**
     * Adds a number of occurrences of the specified element to this multiset.
     *
     * @param element the element to add
     * @param occurrences the number of occurrences to add
     * @return the previous count of the element before the operation; possibly zero
     * @throws IllegalArgumentException if {@code occurrences} is negative, or if the resulting
     *     amount would exceed {@link Integer#MAX_VALUE}
     */

    boolean addedPredecessor;

    if (previousValue == null) {
      addedPredecessor = true;
    } else if (previousValue instanceof PredAndSucc) {
      // Restore previous PredAndSucc object.
      adjacentNodeValues.put(node, previousValue);
      addedPredecessor = false;
    } else if (previousValue != PRED) { // successor

    @Override
    public ReferenceEntry<K, V> getPreviousInAccessQueue() {
      return previousAccess;
    }

    @Override
    public void setPreviousInAccessQueue(ReferenceEntry<K, V> previous) {
      this.previousAccess = previous;
    }

    private long writeTime = Long.MAX_VALUE;

    @Override
    public long getWriteTime() {
      return writeTime;
    }

    @Override

    @Override
    public ReferenceEntry<K, V> getPreviousInAccessQueue() {
      return previousAccess;
    }

    @Override
    public void setPreviousInAccessQueue(ReferenceEntry<K, V> previous) {
      this.previousAccess = previous;
    }

    private long writeTime = Long.MAX_VALUE;

    @Override
    public long getWriteTime() {
      return writeTime;
    }

    @Override

   * that would have been produced in that idle time). So, if rate == 1 permit per second, and
   * arrivals come exactly one second after the previous, then storedPermits is _never_ increased --
   * we would only increase it for arrivals _later_ than the expected one second.
   */

  /**

  /**
   * Adds a number of occurrences of the specified element to this multiset.
   *
   * @param element the element to add
   * @param occurrences the number of occurrences to add
   * @return the previous count of the element before the operation; possibly zero
   * @throws IllegalArgumentException if {@code occurrences} is negative, or if the resulting amount
   *     would exceed {@link Integer#MAX_VALUE}
   */

    /**
     * Adds a number of occurrences of the specified element to this multiset.
     *
     * @param element the element to add
     * @param occurrences the number of occurrences to add
     * @return the previous count of the element before the operation; possibly zero
     * @throws IllegalArgumentException if {@code occurrences} is negative, or if the resulting
     *     amount would exceed {@link Integer#MAX_VALUE}
     */

          @Override
          public boolean hasNext() {
            return listIter.hasPrevious();
          }

          @Override
          public T next() {
            return listIter.previous();
          }

          @Override
          public void remove() {
            listIter.remove();
          }
        };
      }
    };
  }

  public void testAdd() {
    ListIterator<String> iterator = create();

    assertTrue(iterator.hasNext());
    assertEquals("a", iterator.next());
    assertEquals("b", iterator.next());
    assertEquals("b", iterator.previous());
    try {
      iterator.add("c");
      fail();
    } catch (UnsupportedOperationException expected) {
    }
  }

  @SuppressWarnings("DoNotCall")
  public void testSet() {

    assertEquals(-1, iterator.previousIndex());
    try {
      iterator.next();
      fail("no exception thrown");
    } catch (NoSuchElementException expected) {
    }
    try {
      iterator.previous();
      fail("no exception thrown");
    } catch (NoSuchElementException expected) {
    }
    try {
      iterator.remove();
      fail("no exception thrown");