title: How to not allow going to a previous page using the phone back button
body: <p>I have my user in the profile page, and to get there you need to go trough the phone authentication and userinfo gathering. But I don't wanna allow them to go back to this two pages, and when I press the back button on my cellphone it does that, how can I fix it? thanks.</p>
  
  <p>I could do something like when this button is pressed it finishes the app, but I don't know how to do it.</p>