title: Group query using mongoose 4.11.0
body: <p>I want to make a group using the last version of mongoose for example:</p>
  
  <pre><code>    Patient.group({gender:true})
      .then((result)=&gt;{
          console.log(result);
      });
  </code></pre>
  
  <p><strong>Patient</strong> is the model, do you know how do this?</p>