This topic came up in a discussion I was having with Yury, and thanks to generators and coroutines, I don't think "f_func" would be the right name for an attribute like this, with something more neutral like "f_origin" potentially being preferable

The specific runtime debugging use case I have in mind is this:

1. Given a frame reference, navigate to the generator-iterator or coroutine that spawned that frame
2. Given gi_back and cr_back doubly-linked counterparts to the current gi_yieldfrom and cr_await introspection attributes on generators and coroutines, expose the relevant generator and/or coroutine stack in addition to the frame stack

These secondary stacks could then potentially be incorporated into traceback outputs by default