title: Python combinations without repetitions
body: <p>I have a list of numbers and I want to make combinations from it. If I have list:</p>
  
  <pre><code>t = [2,2,2,2,4]
  c = list(itertools.combinations(t, 4))
  </code></pre>
  
  <p>The result is:</p>
  
  <pre><code>(2, 2, 2, 2)
  (2, 2, 2, 4)
  (2, 2, 2, 4)
  (2, 2, 2, 4)
  (2, 2, 2, 4)
  </code></pre>
  
  <p>but I want to get:</p>
  
  <pre><code>(2, 2, 2, 2)
  (2, 2, 2, 4)
  </code></pre>
  
  <p>Is it possible to eliminate duplicates except making new list and going through first list?</p>