title: Passing a pointer to a list in Python
body: <p>Is there any way to pass a pointer to a list, so I could have
  <code>update_list(list, data)</code></p>
  
  <p>Instead of having to do
  <code>list = update_list(list, data)</code></p>
  
  <p>Independent of whether this is possible, what is advisable and Pythonic in this situation?</p>