title: $.grep returns type void is not assignable to type boolean
body: <p>I'm trying to use the code below in my <code>TypeScript</code> code, but it returns an error all the time:</p>
  
  <pre><code>$.grep(user, function(m,i) {
      return ( n !== 5 &amp;&amp; i &gt; 4 );
  });
  </code></pre>
  
  <p>It's <code>function</code> that get marked with: </p>
  
  <blockquote>
    <p>type void is not assignable to type boolean</p>
  </blockquote>
  
  <p>Can anyone tell me why i cant do this?</p>