Create branches with curves sorted by z values

Hello everyone

After running a contour, I am in need of moving each of the contour layers. They are many so this is perfect for gh.

Each of these layers contains many curves that have same z value.

I need to group all of the layers into branches to then apply a move vector to each branch.

I have found some definitions that sort items on based on z value, but they work with ranges. I need to work with specific values.

Uploaded wip def.

Thank you.