Perhaps this is stupendously obvious, but how do I change the default margin width from 120 to a pep-8 compliant 79? I'm using PyCharm 2.7.2. I've seen plenty of settings options to disable or change the behavior of the margins, but none to change the width.
I expected it would be under one of the following, but no dice:
..where does this (surely obvious) configuration option live?