style: 'circle' // square, circle
      },
      shaded: {
        orientation: 'top' // top, bottom
      }
    }});

  var container = document.getElementById('visualization');
  var items = [
    {x: '2014-06-12', y: 0 , group: 0},
    {x: '2014-06-13', y: 30, group: 0},
    {x: '2014-06-14', y: 10, group: 0},
    {x: '2014-06-15', y: 15, group: 1},
    {x: '2014-06-16', y: 30, group: 1},
    {x: '2014-06-17', y: 10, group: 1},
    {x: '2014-06-18', y: 15, group: 1},
    {x: '2014-06-19', y: 52, group: 1