How does one access $scope from a ui-grid cell template? Here's my controller code:

app.controller('MainCtrl', ['$scope', function ($scope) {



  // i want to reference this from a cell template.

  $scope.world = function() { return 'world'; };



  $scope.gridOptions = {

    data: [

      { id: item1 },

      { id: item2 }

    ],

    columnDefs: [

    {

      field: 'id',



      // world() is never called and is not displayed.

      cellTemplate: '<div>{{ hello  + world() }}</div>'

    }]

  };

}]);

See it in action here:
http://plnkr.co/edit/WYXeQShHWKDYDs4MIZnP?p=preview

I would expect cell contents to show hello world, but they just show hello.