Comment 2 for bug 1386424

Pyflakes has no concept of "warnings". It only has errors, and Pyflakes on principle emits errors only about things it is sure are errors. This is a useful property that similar tools do not have: you can run Pyflakes on any codebase, and it shouldn't spew any errors unless there are really errors in the program.

flake8 adds pep8 checking to pyflakes, which is a good option if you like pyflakes but want checks that are predicated on style and opinion. pylint and pychecker are unrelated to pyflakes, but also do style-based checks. You might evaluate those tools to see if they better suit your needs.