That does feel a lot clearer

I guess my main thing is I don't know if I should trust my understanding of the tree display or not

Perhaps, as a sort-of training assistant, have the resulting "code" optionally appear beside the editor?

e.g. https://i.imgur.com/92stVmi.png

(I also noticed that you are looking for TCO for python, In some cases Coconut can do TCO, and can compile to python, but its somewhat of an unweildly tool to use

http://coconut.readthedocs.io/en/v1.2.2/DOCS.html#function-d... )