code: 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
      };
  }
docs: @ngdoc directive
  @name chartSize
  @description
  `chart-size` is used to configure size properties of the chart.
  
  Restrict To:
  Element
  
  Parent Element:
  c3chart
  
  @param {Number} chartWidth Width of the chart element, by default it will be
  calculated from the parent container.
  
  {@link http://c3js.org/reference.html#size-width| c3js docs}
  
  @param {Number} chartHeight Height of the chart element, by default it will be
  calculated from the parent container.
  
  {@link http://c3js.org/reference.html#size-height| c3js docs}
  
  @example
  Usage:
  <chart-size chart-height="..." chart-width="..."/>
  
  Example:
  {@link http://jettro.github.io/c3-angular-directive/#examples}
  
  <chart-size chart-height="600" chart-width="600"/>