Log Message:
py-flakes: updated to 2.0.0

2.0.0 (2018-05-20)
- Drop support for EOL Python <2.7 and 3.2-3.3
- Check for unused exception binding in except: block
- Handle string literal type annotations
- Ignore redefinitions of _, unless originally defined by import
- Support __class__ without self in Python 3
- Issue an error for raise NotImplemented(...)