title: Drupal 7 How to use render element instead of variables in hook_theme()
body: <p>I'm having trouble understanding the 'render element' key purpose when implementing hook_theme().</p>
  
  <pre><code>function personal_news_theme($existing, $type, $theme, $path) {
    return array(
      'teaser_list_by_user' =&gt; array(
        'render element' =&gt; 'element',
      ),
    );
  }
  </code></pre>
  
  <p>I did my research and the way I understand it, the <code>render element</code> key is use when creating a theme function to modify another theme function's output ONLY! And there's no way to use it as to implement a new theme function.
  If I'm wrong, how can I use it instead of <code>variables</code>?</p>