title: How to move code of an inner class to different file (Python)?
body: <p>Assume I have some class with an inner class:</p>
  
  <pre><code>class A:
     class B:
        ...
     ...
  </code></pre>
  
  <p>I would like to implement class <code>B</code> in a different file than the code for class <code>A</code> to increase readability.</p>
  
  <p>How can this be accomplished?</p>
  
  <hr>
  
  <p>EDIT:  I don't want <code>B</code> to be accessible in any way other than <code>A.B</code>.</p>