title: Mypy "class module" annotation
body: <p>I have a function <code>load_config</code> that loads and returns a python module:</p>
  
  <pre><code>import imp
  
  def load_config(path: str):
      return imp.load_source('config', path)
  
  print(type(load_config('config.py')))
  </code></pre>
  
  <p>This snippet prints <code>&lt;class 'module'&gt;</code>.</p>
  
  <p>How do I annotate <code>load_config</code> return value with Mypy?</p>