Iterator over tree ends

[ghost]

Is there a walker method that efficiently returns the elements at the end of the tree (leaves)?

I took a look at the raw nodes and it looks like all of the leaf nodes have a next value that looks like next: [EdgeIndex(End), EdgeIndex(6)]. So I could call filter on a recursive walk over all of the nodes in the tree or on .raw_nodes() and check if next[0] == EdgeIndex(End), but that seems like a waste. Is there a better way to do this using the currently available API?

[ghost]

For reference, this is an example of what I'm going with for now:

let end_index = EdgeIndex::<u32>::end();
let leaves: Vec<Node> = tree.raw_nodes().iter().filter(|&node| {
      node.next_edge(EdgeDirection::Outgoing) == end_index
    }).collect();

[hellow554]

Related: https://github.com/mitchmindtree/daggy/issues/24