Often when people talk about trees as data structure what they actually want are DAGs (e.g. filesystems usually are used as DAGs not trees, because they can hav

Often when people talk about trees as data structure what they actually want are DAGs (e.g. filesystems usually are used as DAGs not trees, because they can have links (although on linux you can actually create cycles in practice people try to avoid it)). Nice to see a good example.