If you're iterating down a node path, you might want to reset a reference. E.g.:

YAML::Node node = /* something */;
for_each(path.begin(), path.end(), [&node](const std::string& key) {
   node.reset(node[key]);
});

or maybe node.set? I was thinking node.reset to mirror a smart pointer, but 
maybe set would be more natural.