Accordion list. Opened all data

I have data with json string and make accardeon list on this example

But when i clicked on list opened all tree’s. What is wrong?

Here is my example:

<html ng-app="ionicApp">
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
    <title>Ionic Accordion</title>
    <link href="//" rel="stylesheet">
    <script src="//"></script>


  <body ng-controller="MyCtrl">
    <ion-header-bar class="bar-positive">
      <h1 class="title">Факультети</h1>

    <ion-content class="padding=2px">
            <div ng-repeat="id in data">
                <ion-item class="item-stable"
                          ng-class="{active: isGroupShown(}">
                    <i class="icon" ng-class="isGroupShown( ? 'ion-android-folder-open' : 'ion-android-folder'"></i>
                <ion-item  class="item-accordion"
                          ng-repeat="sm in id.items"
                          ng-show="isGroupShown(" a href="#" >
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