docs: function(key, marker, seriesData){
      var markers = {},
          data = [],
          values,
          i,
          seriesData = seriesData || [];
  
      markers[key] = marker;
  
      for (i = 0; i < seriesData.length; i++) {
        values = {};
        values[key] = seriesData[i];
        data.push(values);
      }
      this.addMarkers(markers, data);
    }