title: What is `return of ()` syntax
body: <p>I'm looking at this snippet of code:</p>
  
  <p><a href="https://i.stack.imgur.com/JZXP5.png" rel="noreferrer"><img src="https://i.stack.imgur.com/JZXP5.png" alt="enter image description here"></a></p>
  
  <p>It's typescript. On the first line there is:</p>
  
  <pre><code>... return of (true);
  </code></pre>
  
  <p>What's this syntax?</p>