title: Remove duplicates from list of lists
body: <p>I have a list containing ~300 lists, however some of them are duplicates and I would like to remove them. I've tried:</p>
  
  <pre><code>cleanlist = [cleanlist.append(x) for x in oldlist if x not in cleanlist]
  </code></pre>
  
  <p>but it keeps throwing <code>RuntimeError: maximum recursion depth exceeded in comparison</code> at me. I tried <code>sys.setrecursionlimit(1500)</code> but that didn't help.</p>
  
  <p>What's a better way to do this?</p>