title: Determine current user in Apps Script
body: <p>I'm trying to identify current user's name to make notes of who edited what like this:</p>
  
  <pre><code>  r.setComment("Edit at " + (new Date()) + " by " + Session.getActiveUser().getEmail());
  </code></pre>
  
  <p>but it won't work - user's name is an empty string.
  Where did I go wrong?</p>