title: How to properly function annotate / type hint a list of strings
body: <p>I am trying to figure out how to properly function annotate or type hint a list of strings. For example, if I had a function like this:</p>
  <pre><code>def send_email(self, from_address: str, to_addresses: list[str]):
      pass
  </code></pre>
  <p><code>to_addresses</code> should be a list of strings.  But when I try to use that annotation I get the following error in my Python 3.4.3 interpreter:</p>
  <p><code>TypeError: 'type' object is not subscriptable</code></p>
  <p>I am positive the <code>list[str]</code> is causing the issue, because if I change it to <code>str</code> the error goes away, but that doesn't properly reflect my intentions for the parameter.</p>