title: how can I use "lang" in gjs?
body: <p>I'm working on Gnome shell extension recently. I looked at some code, like this:</p>
  <pre><code>const Lang = imports.lang;
  
  const extension = new Lang.Class({...}）
  </code></pre>
  <p>I can't find any information about Lang in GJS.</p>
  <p>Where should I go to find the relevant development manual?</p>