title: Indicating multiple value in a Dict[] for type hints
body: <p>How do I express the type of a <code>Dict</code> which has two keys that take two different types of values? For example:</p>
  
  <pre><code>a = {'1': [], '2': {})
  </code></pre>
  
  <p>The following is just to give you an idea of what I am looking for.</p>
  
  <blockquote>
    <p>Dict[(str, List), (str, Set)]</p>
  </blockquote>