title: How to access custom XML elements via SimpleXML
body: <p>How can I access custom XML elements via SimpleXML. So if I have:</p>
  
  <pre><code>&lt;rss&gt;
     &lt;custom:element&gt;&lt;/custom:element&gt;
  &lt;/rss&gt;
  </code></pre>
  
  <p>Right now these elements are simply being ignored when I pass them into <code>simplexml_load_string()</code>.</p>