title: optional list argument "list = list or []" in python
body: <p>Conventional way of dealing with optional list arguments is the following:</p>
  
  <pre><code>def func(list_of_vals = None):
     if list_of_vals is None:
        list_of_vals = []
     ...
  </code></pre>
  
  <p>I wounder if the following (shorter) version has any pitfalls? why nobody do that? is it considered more obscure?</p>
  
  <pre><code>list_of_vals = list_of_vals or []
  </code></pre>