title: Python - unpack list of lists
body: <p>What is the cleanest way to implement the following:</p>
  
  <pre><code>list = [list1, list2, ...]
  return [*list1, *list2, ...]
  </code></pre>
  
  <p>It looks like this syntax will be available in Python 3.5. In the meantime, what is your solution?</p>