title: Pass class type as argument to class constructor
body: <p>Say I have a <code>Directory</code> class which accepts a list of other sub-directories as an argument:</p>
  <pre><code>class File:
      pass
  
  class Directory:
      def __init__(self, directories: List[Directory], files: List[File]):
                                           ^^^^^^^^^
          self.directories = directories
          self.files = files
  </code></pre>
  <p>I am getting an error saying <code>&quot;Directory&quot; is not defined</code>. This code works just fine if I don't pass the types, but how do you handle this use-case in python?</p>