Check out your GitHub pull request with an interactive shell menu

When I want to check out a GitHub pull request of my colleagues on my local machine, I usually have to open my browser, go to the pull request page on GitHub, copy the branch name, do a git fetch in my terminal, followed by a git checkout, pasting the branch name. Annoyed by this context switch between terminal and browser and all that mouse movement, I devised a way to select the pull request from a list in the terminal, with a checkout when I hit Enter: