Missing parametter `seen` in docstring
That's used internally to avoid cycles in graph when recursing. Ignore. Could you maybe rename it `_seen` and note it in the docstring just in case ? :) So you don't have other questions ;)
As `seen` here (lol)

https://github.com/coleifer/peewee/blob/a6198b96f475a2ee9687f36eda1cbb539907c56a/playhouse/shortcuts.py#L14-L32

Cheers!