title: I need some help promises and q library
body: <p>I need some help on syntax with <code>node.js promises</code>. In readme for <code>node.js</code> module called q <a href="https://github.com/kriskowal/q" rel="nofollow">https://github.com/kriskowal/q</a> is written something I don't understand.</p>
  
  <p>Why do they always write <code>return</code> before <code>promise</code>?</p>
  
  <pre><code>return Q.fcall(eventualAdd, 2, 2);
  </code></pre>
  
  <p>How do I make an asynchronous function with callback into function that returns <code>promise</code>? I try</p>
  
  <pre><code>function doThis(a,b, callback) { var result = a+ b; setTimeout( callback, 2000, result);}
  Q.ncall(doThis, 2,3).then( function(result) { alert(result); });
  </code></pre>
  
  <p>I think after 2000 it must alert with 5 but nothing happens.</p>