title: No TypeError comparing int with None in Python3
body: <p>I understand that comparing int and None types is not valid in Python3 (3.6.1) as I see here:</p>
  
  <pre><code>&gt;&gt;&gt; largest = None
  &gt;&gt;&gt; number = 5
  &gt;&gt;&gt; number &gt; largest
  TypeError: '&gt;' not supported between instances of int and NoneType
  </code></pre>
  
  <p>But inside this script it doesn't give a TypeError.</p>
  
  <pre><code>largest = None
  for number in [5, 20, 11]:
      if largest is None or number &gt; largest:
          largest = number
  </code></pre>
  
  <p>When I run this script with python3 it runs without a TypeError. Why?</p>