Minor Description
To enable easier spotting bugs and enable code/workflow native to Python developers, we should include python linter (flake8) and static type checking (mypy) to the repo. This issue suggest reformatting python client code to pep8 following discussion in https://reviews.apache.org/r/73097/
By running flake8/mypy just once we can easily spot obvious issues and reformat the code so it follows best-practices regarding Python development. It also helps developers using Python dedicated IDE to work in more native workflow.