}
      next = current = previous;
      previous = previous.previous;
      nextIndex--;
      return current;
    }

    @Override
    public int nextIndex() {
      return nextIndex;
    }

    @Override
    public int previousIndex() {
      return nextIndex - 1;
    }

    @Override
    public void set(Entry<K, V> e) {

       */
      return nextIndex >= 0;
    }

    /**
     * Checks whether nextIndex is valid; if so setting nextItem. Stops iterator when either hits
     * putIndex or sees null item.
     */
    private void checkNext() {
      if (nextIndex == putIndex) {
        nextIndex = -1;
        nextItem = null;
      } else {
        nextItem = items[nextIndex];

        }
      };
  Stimulus<E, ListIterator<E>> nextIndex =
      new Stimulus<E, ListIterator<E>>("nextIndex") {
        @Override
        void executeAndCompare(ListIterator<E> reference, ListIterator<E> target) {
          assertEquals(reference.nextIndex(), target.nextIndex());
        }
      };
  Stimulus<E, ListIterator<E>> previousIndex =

        }
      };
  Stimulus<E, ListIterator<E>> nextIndex =
      new Stimulus<E, ListIterator<E>>("nextIndex") {
        @Override
        void executeAndCompare(ListIterator<E> reference, ListIterator<E> target) {
          assertEquals(reference.nextIndex(), target.nextIndex());
        }
      };
  Stimulus<E, ListIterator<E>> previousIndex =

  }

  @Override
  @ParametricNullness
  public final T previous() {
    return transform(backingIterator().previous());
  }

  @Override
  public final int nextIndex() {
    return backingIterator().nextIndex();
  }

  @Override
  public final int previousIndex() {
    return backingIterator().previousIndex();
  }

  @Override
  public void set(@ParametricNullness T element) {

  }

  @Override
  @ParametricNullness
  public final T previous() {
    return transform(backingIterator().previous());
  }

  @Override
  public final int nextIndex() {
    return backingIterator().nextIndex();
  }

  @Override
  public final int previousIndex() {
    return backingIterator().previousIndex();
  }

  @Override
  public void set(@ParametricNullness T element) {

    if (list.size() != axes.size()) {
      return -1;
    }
    ListIterator<?> itr = list.listIterator();
    int computedIndex = 0;
    while (itr.hasNext()) {
      int axisIndex = itr.nextIndex();
      int elemIndex = axes.get(axisIndex).indexOf(itr.next());
      if (elemIndex == -1) {
        return -1;
      }
      computedIndex += elemIndex * axesSizeProduct[axisIndex + 1];
    }

    if (list.size() != axes.size()) {
      return -1;
    }
    ListIterator<?> itr = list.listIterator();
    int computedIndex = 0;
    while (itr.hasNext()) {
      int axisIndex = itr.nextIndex();
      int elemIndex = axes.get(axisIndex).indexOf(itr.next());
      if (elemIndex == -1) {
        return -1;
      }
      computedIndex += elemIndex * axesSizeProduct[axisIndex + 1];
    }

    public T next() {
      if (!hasNext()) {
        throw new NoSuchElementException();
      }
      T result = result(entryIndex);
      toRemove = entryIndex;
      entryIndex = backingMap.nextIndex(entryIndex);
      return result;
    }

    @Override
    public void remove() {
      checkForConcurrentModification();
      CollectPreconditions.checkRemove(toRemove != -1);

        }
        return array[i++];
      }

      @Override
      public boolean hasPrevious() {
        return i > 0;
      }

      @Override
      public int nextIndex() {
        return i;
      }

      @Override
      public String previous() {
        if (!hasPrevious()) {
          throw new NoSuchElementException();
        }
        return array[--i];
      }