title: Add a loop until user inputs a valid answer?
body: <p>I want to add a loop to this:</p>
  
  <pre><code>question = raw_input("Reboot Y/N ")
  if len(question) &gt; 0 and question.isalpha():
      answer = question.upper()
      if answer == "Y":
          print "Reboot"
      elif answer == "N":
          print "Reboot Cancled"
      else:
          print "/ERROR/"
  </code></pre>
  
  <p>So if the user inputs anything else the error appears and sends them back to the question. </p>