title: Anonymous closure argument not contained in a closure
body: <p>Why doesn't this code work?</p>
  
  <pre><code>func function (param1 : Int, param2 : Int) -&gt; Int {
      return $0 + $1
  }
  </code></pre>
  
  <p>It produces an error:</p>
  
  <blockquote>
    <p>Error: Anonymous closure argument not contained in a closure</p>
  </blockquote>