title: How to use ngChange in custom directive
body: <p>I want to create directive for toggle button, I have code that I want to put into directive:</p>
  
  <pre><code>&lt;div class="toggle-button" ng-class="{true: toggleTrue === true, false: toggleTrue === false}"&gt;
      &lt;button class="true" ng-click="toggleTrue = true"&gt;Y&lt;/button&gt;&lt;button class="false" ng-click="toggleTrue = false"&gt;N&lt;/button&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>(I only work on style change, that's why I have only class change)</p>
  
  <p>I want to have something like:</p>
  
  <pre><code>&lt;toogle ng-change="SomeFunction()" ng-model="someValue" /&gt;
  </code></pre>
  
  <p>how can I work with ng-change in my directive? Should I just parse attr or use scope attribute or is there a code like with ngModel that need to be use together with ngChange.</p>