title: Call class instance from another class
body: <p>Is there anything wrong with this kind of structure?  Is there a more pythonic way to do something like this?</p>
  
  <p>The backend class has a variety of data manipulation methods.  Frontend main method is a state machine that deals with Kivy UI (button deactivation logic, control screens, etc)</p>
  
  <pre><code>class Backend:
      def one(self):
          pass
  
  class Frontend:
      def main(self):
          B.one()
  
  B = Backend()
  F = Frontend()
  F.main()
  </code></pre>