title: How can I type hint an attribute in Python 3.5?
body: <p>I have a class where I want the initial value of an attribute to be <code>None</code>:</p>
  
  <pre><code>class SomeClass:
      def __init__(self):
          self.some_attribute = None
  </code></pre>
  
  <p>How can I add type hinting, so that the IDE understands that <code>some_attribute</code> is usually of the type <code>AnotherClass</code>?</p>