twVolc

I haven't tried this but it's very likely the problem is the same as #466. Presumably you need to pass the custom object of iou_score when you load the model.

Just to say that this installation now fails on Windows. I've followed the installation instructions but pip seems to hit an error with `gym`. ``` raise InvalidRequirement(str(e)) from e wheel.vendored.packaging.requirements.InvalidRequirement:...

Not really a great solution but I just installed the ML3 environment for the latest version of the book instead, and this environment installed successfully. I haven't worked through too...