PEP8 (the generally-used Python style guide for any non-Python people reading along) defaults to 79 characters, with an option to increase it to 99. Personally

PEP8 (the generally-used Python style guide for any non-Python people reading along) defaults to 79 characters, with an option to increase it to 99. Personally I'm fine with either option, but I think lines much longer than 99 characters start to get pretty awkward. If you really do need longer lines than that occasionally you can mark an exception for whatever style checker you're using.