title: TypeError: unsupported operand type(s) for &: 'set' and 'tuple'
body: <p>I keep getting this error:</p>
  
  <pre><code>File "C:\Users\Jake\SkyDrive\Documents\_Jake's Documents\School\2013 Fall\CSCI\Final Project\word_game.py", line 57, in callback
  if len(input_set &amp; user_set) == 0:
  TypeError: unsupported operand type(s) for &amp;: 'set' and 'tuple'
  </code></pre>
  
  <p>'user_set' is a combination of four sets. Is that why it's giving me this?</p>