title: How to use Python tkSimpleDialog.askstring
body: <p>I want to use the response from an askstring prompt to set a variable. Unfortunately,
  I have the dilemma that I'm trapped in the loop asking the question or the window refuses to draw because the variable (urltoopen) has no value. 
  The code as it stands:</p>
  
  <pre><code>urltoopen = tkSimpleDialog.askstring('Address', 'Where do we get the pictures from?')
  usock = urllib2.urlopen(urltoopen)
  data = usock.read()    
  usock.close()                     
  </code></pre>