title: custom claim for multi sub users at once using cloud function?
body: <p>What is the best way to update the custom claim of multiple sub users at once using a cloud function ?
  I mean is would a forEach on an array of lets say a list of users emails (strings) do this job ?</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>const list = ['user1@example.com','user2@example.com','user3@example.com']
  
  
  list.forEach((el)=&gt;
  getAuth()
    .getUserByEmail(el)
    .then((user) =&gt; {
        return getAuth().setCustomUserClaims(user.uid, {
          premium : true,
        });
    })
    .catch((error) =&gt; {
      console.log(error);
    });
    
    )</code></pre>
  </div>
  </div>
  </p>