[collections] Any ObjectGraphIterator examples that return more than just leaf nodes

[breekie]

I've been taking a look at the ObjectGraphIterator and the example of a 
Transformer that can continue through the iterators (Forest, Tree, Branch, 
Leaf) and return the Leaf nodes.  Is it possible to have a Transformer that 
would return a Branch node if no Leaf node existed?

Thanks In Advance,
Brendan