code: @Deprecated
    public final FluentIterable<T> postOrderTraversal(final T root) {
      checkNotNull(root);
      return new FluentIterable<T>() {
        @Override
        public UnmodifiableIterator<T> iterator() {
          return postOrderIterator(root);
        }
  
        @Override
        public void forEach(Consumer<? super T> action) {
          checkNotNull(action);
          new Consumer<T>() {
            @Override
            public void accept(T t) {
              children(t).forEach(this);
              action.accept(t);
            }
          }.accept(root);
        }
      };
    }
docs: Returns an unmodifiable iterable over the nodes in a tree structure, using post-order
  traversal. That is, each node's subtrees are traversed before the node itself is returned.
  
  <p>No guarantees are made about the behavior of the traversal when nodes change while iteration
  is in progress or when the iterators generated by {@link #children} are advanced.
  
  @deprecated Use {@link com.google.common.graph.Traverser#depthFirstPostOrder} instead, which
  has the same behavior.