Slicing gradients

[sethgi]

mainly added return_grads to batchZonotope.slice

also commented out a bug-inducing error check in compress.py

finally, ran a linter on batch_zono.py

[BuildingAtom]

Thanks, this looks good! Could you also add return_grads for zonotope.slice following that same form as well? I think we'll want to revisit the zonotope API's later, but that's a future thing.

As for the error check in compress.py. I took another look at it, and it seems like that was some internal leftover from checking downstream tasks for over-approximation, so we're good to remove it.