angular-ui-bootstrap accordion collapse/expand all

I would like to create a collpase/expand all button for a set of accordions. I am using angular.js v1.2.6 and angular-bootstrap-ui 0.9.0. I haven't been able to find an example of how to do a collpase/expand all. I'm an angular novice and any advice or suggestions is appreciated.

ALSO, I should add that the solution in this post doesn't work in the newer version of angular.js (v1.0.8 vs v1.2.6) that I am using (which is a latest version at the time of this posting). In the newer version it throws an error about trying to create two isolated scopes.

Markup:

    <div ng-controller="myCtlr">

     <accordion close-others="oneAtATime">

     <button class="btn" ng-click="section.isCollapsed = !section.isCollapsed">Toggle Sections</button>

      <accordion-group ng-repeat="section in sections" is-open="section.isOpen">
       <accordion-heading>
        <div class="accordion-heading-content" ng:class="{collapsed: section.isOpen}">
          {{section.name}}
        </div>
       </accordion-heading>
        Section content
      </accordion-group>

     </accordion>

   </div>

JS:

var theapp = angular.module('myApp', [
  'ui.bootstrap'
])

function myCtlr ($scope) {
 $scope.isCollapsed = false;
 $scope.sections = [
    {'id': '353','otherid': '7','name': 'One','Sequence': '1'},
    {'id': '354','otherid': '8','name': 'Two','Sequence': '1'},
    {'id': '355','otherid': '9','name': 'Three','Sequence': '1'}
];

}