Frankly? Because my editor tells me to. But now that you've actually asked me to think about the esthetics of this particular piece of code and have to say: I don't give a damn. It just looked better to me that way and pleased the nagging of my editor. Feel free to tell me to change it back but don't ask me to write novels about why. In case you want to know there are others not liking the style: https://github.com/jcrocholl/pep8/issues/126