Vis.js -如何让graph2d条形图显示延伸到终点的条形图？

var container = document.getElementById('visualization');
var data = new vis.DataSet([
  {x: '2019-01-01', y: 10},
  {x: '2019-02-01', y: 15},
  {x: '2019-03-01', y: 20}
]);
var options = {
  drawPoints: false,
  shaded: {
    orientation: 'bottom'
  }
};
var graph2d = new vis.Graph2d(container, data, options);