title: All combinations of a list of lists
body: <p>I'm basically looking for a python version of <a href="https://stackoverflow.com/questions/545703/combination-of-listlistint">Combination of <code>List&lt;List&lt;int&gt;&gt;</code></a></p>
  
  <p>Given a list of lists, I need a new list that gives all the possible combinations of items between the lists.</p>
  
  <pre><code>[[1,2,3],[4,5,6],[7,8,9,10]] -&gt; [[1,4,7],[1,4,8],...,[3,6,10]]
  </code></pre>
  
  <p>The number of lists is unknown, so I need something that works for all cases. Bonus points for elegance!</p>