Flake8 is a command-line tool for linting Python projects. 
 By default, it includes lint checks provided Pyflakes, pycodestyle, and McCabe
 It's also a platform, and allows plugins to extend the checks.
 Flake8 will run third-party extensions if they are found and installed.

But what does all of that mean?

Anthony Sottile is a maintainer of flake8 and has kindly offered to explain it to us.

Links:

• Flake8: Your Tool For Style Guide Enforcement
• pyflakes
• pycodestyle
• mccabe
• pyflakes/messages.py
• flake8 Error / Violation Codes
• wemake-python-styleguide
• flake8-typing-imports
• tox automation project
• Nox
• pre-commit