title: How can I identify when a Button is released in Tkinter?
body: <p>I'm using Tkinter to make a GUI and drive a robot. </p>
  
  <p>I have 4 Buttons: <code>FORWARD</code>, <code>RIGHT</code>, <code>BACKWARD</code> and <code>LEFT</code>. I want to make the robot move as long as the Button is being pressed, and stop when the Button is released.</p>
  
  <p>How can I identify when a Button is released in Tkinter?</p>