title: Display item in legend even if value = 0 with Google Charts Tools Pie Chart
body: <p>I'm using Google Charts Tools, specifically the <a href="https://google-developers.appspot.com/chart/interactive/docs/gallery/piechart">Pie Chart</a>. </p>
  
  <p>Naturally, if a item has a value of 0, it is not displayed in the pie (since it occupies 0% of the pie). However, it doesn't display in the legend either. </p>
  
  <p>How can I manipulate the initialization options to still show a 0 value item in the legend, so that users can see that the item exists, it just has a 0 value?</p>