Some implementation of "secure" deleting nodes

Hello,

I'm trying to implement function to delete nodes, similary to rename, so there is a button, I select a node, click button and that node is deleting. Everything is clear, but, of security reason i want give user option to delete only with node which don't contain any child nodes. Is it possible? I've found a function contain() but i don't know how to use this. By the way, your class is really great, but in documentation, there are missing example how to use each function.

Thank you contribution
Regards
Paul