docs: function ChartSize() {
      var sizeLinker = function (scope, element, attrs, chartCtrl) {
          var chartSize = null;
          var width = attrs.chartWidth;
          var height = attrs.chartHeight;
          if (width || height) {
              chartSize = {};
              if (width) {
                  chartSize.width = parseInt(width);
              }
              if (height) {
                  chartSize.height = parseInt(height);
              }
              chartCtrl.addSize(chartSize);
          }
      };
  
      return {
          "require": "^c3chart",
          "restrict": "E",
          "scope": {},
          "replace": true,
          "link": sizeLinker
      };
  }