title: dc.js piechart legend - hide if result is 0
body: <p>Is it possible to remove/hide the legends for a piechart if the result is 0?</p>
  
  <p>I have a piechart that has quite a few items in the legend, when there has been some filtering it would be great to remove the legends that are not available.</p>
  
  <p>Any help would be appreciated.</p>