If settings.toml contains:

A_NUMBER = 123

os.getenv("A_NUMBER") will return the int 123.

This is non-standard compared with CPython, where os.getenv() always returns a string or None.

This came up because I was thinking about adding TOML bool support (true and false) to what we can parse in settings.toml.

I'm not sure this is worth fixing, but I think it's possible to fix.