1. I **wonder** if the tutorial section about selections shouldn't be updated ?
Yes indeed. Thanks for keeping my lazyness in check 😄.
2. I **wonder** if all the logic about keys should not be moved from the `group.py` module to a separate new module (since, as I understand it, the functions present in `group.py` are also used in `axis.py` and `array.py`)?
That would make sense but I don't know if that's easily feasible (cyclic imports etc.). Needs to check.