title: python: flake8 cannot find non exising method
body: <p>If I do something like:</p>
  
  <pre><code>new_list = []
  new_list.foo()
  </code></pre>
  
  <p>flake8 does not return an error for foo() method since it is not a 'list' method. </p>
  
  <p>Is this normal or do I need to configure something?</p>