title: Python countdown clock with GUI
body: <p>I'm having problems with a countdown clock that I was making in Python for a Raspberry Pi. I need to have a countdown clock that counts down from 60 minutes. When time runs out it should display a red text "GAME OVER". </p>
  
  <p>I've already made one using TKinter and a <code>for</code> loop for the actual timer but I couldn't find any way to stop the <code>for</code> loop. I gave up on it.</p>
  
  <p>Is there anyone nice enough to maybe write the actual timer and timer stopping part? I'm good enough at python and TKinter to do everything else that I need.</p>