title: How to go back to first if statement if no choices are valid
body: <p>How can I have Python move to the top of an if statement if no condition is satisfied correctly.</p>
  
  <p>I have a basic if/else statement like this:</p>
  
  <pre><code>print "pick a number, 1 or 2"
  a = int(raw_input("&gt; ")
  
  if a == 1:
      print "this"
  if a == 2:
      print "that"
  else:
     print "you have made an invalid choice, try again."
  </code></pre>
  
  <p>What I want is to prompt the user to make another choice for this if statement without them having to restart the entire program, but am very new to Python and am having trouble finding the answer online anywhere.</p>