Download the example or clone the whole project:

curl https://codeload.github.com/palmerhq/backpack/tar.gz/master | tar -xz --strip=2 backpack-master/examples/with-flowtype
cd with-flowtype

Install it and run:

npm install
npm run dev

This demonstrates how to add Flow to your Backpack project. Flow is a static type checker that helps you write code with fewer bugs. Check out this introduction to using static types in JavaScript if you are new to this concept.

To learn more about Flow, take a look at its documentation.