title: How to name a Python file that cosists only of a class definition?
body: <p>If I have a Python file that consists only of a class definition, how should I name it?</p>
  
  <p>For example, if I have this:</p>
  
  <pre><code>class Folder:
      """Represents a computer folder."""
      ...
  </code></pre>
  
  <p>, should I name the file <strong>folder.py</strong> or <strong>Folder.py</strong>? And what is the case if the file has (a) function definition(s) too?</p>