title: Testing whether class variable is repeatedly defined
body: <p>Here is a quick example:</p>
  
  <pre><code>class KEY(object):
      A = 'a'
      A = 'b'
      B = 'b'
  </code></pre>
  
  <p>Is there a way to test that 'A' has been repeatedly defined in class 'KEY' regardless of the assigned value?</p>