title: NameError: name 'List' is not defined
body: <p>I'm really unsure why this isn't working. Here is the important part of the code (it's from a leetcode challenge).
  The first line throws the NameError.</p>
  
  <pre class="lang-py prettyprint-override"><code>def totalFruit(self, tree: List[int]) -&gt; int:
      pass
  </code></pre>
  
  <p>If I try importing <code>List</code> first I get an error <code>No module named 'List'</code>. I'm using Python 3.7.3 from Anaconda.</p>