ImmutableSet<N> validated = validate(startNodes);
    return new Iterable<N>() {
      @Override
      public Iterator<N> iterator() {
        return newTraversal().postOrder(validated.iterator());
      }
    };
  }

  abstract Traversal<N> newTraversal();

  @SuppressWarnings("CheckReturnValue")
  private ImmutableSet<N> validate(Iterable<? extends N> startNodes) {

   *
   * <p>Note however that if your escaper does not escape characters in the supplementary range, you
   * should either continue to validate the correctness of any surrogate characters encountered or
   * provide a clear warning to users that your escaper does not validate its input.
   *
   * <p>See {@link com.google.common.net.PercentEscaper} for an example.
   *
   * @param csq a sequence of characters

      DIGIT_MATCHER.or(LETTER_MATCHER).or(DASH_MATCHER);

  /**
   * Helper method for {@link #validateSyntax(List)}. Validates that one part of a domain name is
   * valid.
   *
   * @param part The domain name part to be validated
   * @param isFinalPart Is this the final (rightmost) domain part?
   * @return Whether the part is valid
   */

    /**
     * If the delegate collection is empty, but the multimap has values for the key, replace the
     * delegate with the new collection for the key.
     *
     * <p>For a subcollection, refresh its ancestor and validate that the ancestor delegate hasn't
     * changed.
     */
    void refreshIfEmpty() {
      if (ancestor != null) {
        ancestor.refreshIfEmpty();
        if (ancestor.getDelegate() != ancestorDelegate) {

        new Receiver<ReferenceEntry<Integer, Integer>>() {
          @Override
          public void accept(ReferenceEntry<Integer, Integer> entry) {
            Integer key = entry.getKey();
            cache.invalidate(key);
          }
        });
  }

  public void testEviction_lru() {
    // test lru within a single segment
    IdentityLoader<Integer> loader = identityLoader();

    int shift2 = shift1 + 10;
    loader.setValuePrefix(shift2);
    // fill with new data - has to live for 20 ms more
    for (int i = 0; i < 10; i++) {
      cache.invalidate(keyPrefix + i);
      assertEquals(
          "key: " + keyPrefix + i, Integer.valueOf(i + shift2), cache.getUnchecked(keyPrefix + i));
    }
    assertEquals(10, CacheTesting.expirationQueueSize(cache));

      return localCache.getIfPresent(key);
    }

    @Override
    public void put(K key, V value) {
      localCache.put(key, value);
    }

    @Override
    public void invalidate(Object key) {
      checkNotNull(key);
      localCache.remove(key);
    }

    @Override
    public void invalidateAll() {
      localCache.clear();
    }

    @Override

     * the key entry's prev or next pointer might point to the dead value entry, and when we
     * put the new entry in the key entry's position in iteration order, it might invalidate
     * the linked list.
     */

    if (oldEntryForValue != null) {
      delete(oldEntryForValue);
    }

    if (oldEntryForKey != null) {
      delete(oldEntryForKey);
    }

      Map<R, Map<C, V>> backingMap, Supplier<? extends Map<C, V>> factory) {
    checkArgument(backingMap.isEmpty());
    checkNotNull(factory);
    // TODO(jlevy): Wrap factory to validate that the supplied maps are empty?
    return new StandardTable<>(backingMap, factory);
  }

  /**
   * Returns a view of a table where each value is transformed by a function. All other properties

  }


  public void testInvalidate_empty() {
    for (LoadingCache<Object, Object> cache : caches()) {
      cache.getUnchecked("a");
      cache.getUnchecked("b");
      cache.invalidate("a");
      cache.invalidate("b");
      cache.invalidate(0);
      checkEmpty(cache);
    }
  }

  public void testInvalidateAll_empty() {
    for (LoadingCache<Object, Object> cache : caches()) {
      cache.getUnchecked("a");