I'd report that bug to the renpy developers. I assume it's assigning your string literal to the notify method, so calling the method later crashes. Hopefully there's a way in Python to protect against that kind of thing.
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I looked into it with a Python developer friend. There is technically a way renpy could protect against this, but it's silly for them to do that to every method. I tried a linter/analyser called "flake8" to try and catch this sort of error but it didn't pick it up. What a strange thing about Python you have discovered :)