1. Fork the repo and create your branch from `master`.

   Open terminal (e.g. Terminal, iTerm, Git Bash or Git Shell) and type:
   ```sh
   git clone https://github.com/<your_username>/jest
   cd jest
   git checkout -b my_branch
   ```
   Note:
   Replace `<your_username>` with your GitHub username

3. Run `yarn install`.
   On Windows:
   To install [Yarn](https://yarnpkg.com/en/docs/install#windows-tab) on Windows you may need to download either node.js or Chocolatey<br />

    ```sh
    yarn install
    ```
    To check your version of Yarn and ensure it's installed you can type:
    ```sh
    yarn --version
    ```