title: Python class definition syntax
body: <p>Is there a difference between</p>
  
  <pre><code>class A:
      ...
  </code></pre>
  
  <p>and</p>
  
  <pre><code>class A():
      ...
  </code></pre>
  
  <p>I just realized that a couple of my classes are defined as the former and they work just fine. Do the empty parenthesis make any difference?</p>