I was wondering if you can explain exactly how the `add_face` function in the poly connectivity class works.

I've been trying to understand how it works by reading the code, but I can't figure all the corner cases.

I've also posted a question here (https://computergraphics.stackexchange.com/questions/8771/halfedge-data-structure-in-openmesh-create-face-function-explanation) which also points the specific bit I don't understand.

Can you help?

Thank you so much.