Plotly stacked line hover

Hover over values to see 0's for lines not specified at that x. Is there a way to hide this?

HTML

<html>
  <head>
  </head>
  <body>
    <div id="test"></div>
    <script src="https://cdn.plot.ly/plotly-latest.min.js"></script>
  </body>
</html>

JavaScript

Plotly.newPlot('test', [{
    line: { shape : 'vh' },
    stackgroup: '1',
    x: [1, 2],
    y: [1, 1],
}, {
    line: { shape : 'vh' },
    stackgroup: '1',
    x: [3, 4],
    y: [2, 2],
}, {
    line: { shape : 'vh' },
    stackgroup: '1',
    x: [3, 4, 5, 6],
    y: [3, 3, 3, 3],
}], {
    hovermode: 'x unified',
    width: '100%',
});