code: function ChartAxis () {
      var axisLinker = function (scope, element, attrs, chartCtrl) {
          var rotate = attrs.axisRotate;
          if (rotate) {
              chartCtrl.rotateAxis();
          }
      };
  
      return {
          "require": "^c3chart",
          "restrict": "E",
          "scope": {},
          "transclude": true,
          "template": "<div ng-transclude></div>",
          "replace": true,
          "link": axisLinker
      };
  }
docs: @ngdoc directive
  @name chartAxis
  @description
  `chart-axis` is used to customize the axis properties. Can be used to change the orientation of the axis.
  
  Restrict To:
  Element
  
  Parent element:
  c3chart
  
  @param {Boolean} axisRotate Configure to rotate the axis, javascript true means we rotate the axis.
  
  {@link http://c3js.org/reference.html#axis-rotated}
  
  @example
  Usage:
  <chart-axis axis-rotate="true"/>
  Example:
  {@link http://jettro.github.io/c3-angular-directive/#examples}