Flow
Implement Flow
Flow types https://flow.org/en/docs/getting-started/ https://github.com/facebook/create-react-app/blob/master/packages/react-scripts/template/README.md#adding-flow
advanced stuff
https://medium.com/flow-type/even-better-support-for-react-in-flow-25b0a3485627 https://medium.com/@linmic/its-time-to-remove-proptypes-and-just-use-flow-for-react-4a3de615aac5