Remove white space at the end of the line. [pep8](https://pypi.python.org/pypi/pep8) is a tool that tells you about these formatting issues. [autopep8](https://pypi.python.org/pypi/autopep8/) will try to fix them for you. There's probably a way to integrate those with whatever editor you're using so you don't have to think about it. 

Not everyone cares about those kinds of things, but I think I'm going to care. ^_^