title: How to get just one file from another branch?
body: <p>I have a <code>master</code> branch with a file called <code>app.js</code>. I made changes to this file on an <code>experiment</code> branch.</p>
  <p>I want to apply only the changes made to <code>app.js</code> from <code>experiment</code> onto the <code>master</code> branch.</p>