Thanks a lot for the PR, this looks like an amazing addition to the library. I have to admit that I do not understand the code fully from taking a first glance but am keen to look into this. Since this is a new feature would you be so kind to point us to some examples we can test this on (without looking at the notebook, I would guess that's a good place to start)? We would need to have tests for this anyway and it might be a good way for us maintainers to get familiar with this feature. This is just an offer, you are also most welcome to implement the tests yourself if you wish.