title: Asterisk in method definition
body: <p>I was looking through the <code>urllib.urlopen</code> method and I saw this in its definition.
  What is meant by this?</p>
  
  <pre><code>def urlopen(url, data=None, timeout=socket._GLOBAL_DEFAULT_TIMEOUT,
              *, cafile=None, capath=None, cadefault=False, context=None):
  </code></pre>
  
  <p>What does it mean?</p>