title: How do you tell if a user is "anonymous" in the onCreate firebase cloud function?
body: <p>Inside my <code>onCreate</code> auth cloud function for firebase handler, how can I tell if the user is anonymous, e.g. the <code>isAnonymous</code> property I get on the client in the <code>onAuthStateChanged</code> or <code>onIdTokenChanged</code> response?</p>
  
  <pre><code>exports.createHandler = functions.auth.user().onCreate((user, context) =&gt; {
    let uid = user.uid,
        isAnonymous = ????;
  });
  </code></pre>