{
    if (err)
      console.log('error:', err);
    else
      console.log(JSON.stringify(response, null, 2));
});</code></pre><h3>Retrieve and Rank</h3><p>Use the <a href="http://watson.stage1.mybluemix.net/smarterplanet/us/en/ibmwatson/developercloud/retrieve-rank.html">Retrieve and Rank</a> service to enhance search results with machine learning.</p>
<pre class="prettyprint source lang-javascript"><code>var retrieve = watson.retrieve_and_rank({
  username: 'INSERT YOUR USERNAME FOR THE SERVICE HERE',
  