Comment 1 for bug 1636146

You seem to be running PyFlakes and Flake8 under python 3. You can verify this by doing `flake8 --version`. basestring is actually *not* defined on Python 3, so if you're writing code for Python 2 (that isn't going to run on Python 3) you should install Flake8 for Python 2 and run it that way too, e.g.,

```
curl -O https://bootstrap.pypa.io/get-pip.py
python2.7 get-pip.py
python2.7 -m pip install flake8
python2.7 -m flake8 libs/proc.py
```