><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramname">req</td><td>the request. </td></tr>
    <tr><td class="paramname">err</td><td>the error to include in the response header. If <code>NULL</code>, no error. </td></tr>
    <tr><td class="paramname">data</td><td>the response data. </td></tr>
    <tr><td class="paramname">len</td><td>the length of the response data.</td></tr>
  </table>
  </dd>
</dl>
<dl class="section note"><dt>Note</dt><dd></dd></dl>
<dl class="section return"><dt