Ion nav button is not working

I have downloaded the side menu project from ionic website and replaced the below lines in “ion-nav-back-button” but when i clicked on side menu, page got opened with out any back button. could you please tell me what are the changes i need to do.

<ion-nav-back-button class="button-clear"ng-click="myGoBack()"><i class="ion-arrow-left-c"></i> Back

which controller has the function myGoBack()?

you could do smthg like this

> <ion-nav-back-button class="button-clear"ng-click="myGoBack()" ng-controller=" mycontroller">
>   <i class="ion-arrow-left-c"></i> Back
> </ion-nav-back-button>


when we use the below lines atleast style should appear, but it is not appearing
<ion-nav-back-button class="button-clear"><i class="ion-arrow-left-c"></i> Back</ion-nav-back-button>