title: Find combinations of a list of sets
body: <p>I'm using python 2.7. Given a list of sets, is there any quick and efficient way to generate the combinations? Input sets always have one item in each set and output sets all have length of 2 <br><br>
  From:</p>
  
  <pre><code>[set(['item1']), set(['item2']), set(['item3'])]
  </code></pre>
  
  <p>To:</p>
  
  <pre><code>[set(['item1','item2']), set(['item2','item3']), set(['item3','item1'])]
  </code></pre>