There's a very minor Pep8 style violation on this line: according to Pep8, Python files should have a newline character at the end.  To fix it, all you have to do is go to the end of the last line and hit "enter" to stick a newline in there.

This isn't something that affects the way the code runs; it's purely stylistic.  Pep8 is a set of style rules for writing easily-readable Python code.  You can find it on the Python website, if you want to read the whole thing.  Fortunately, we don't have to: one of the reasons that we have SublimeLinter set up with flake8 is to catch style violations like this for us.