title: pylint not-an-iterable error when subclassing List[int]
body: <p>Code example:</p>
  <pre><code>from typing import List
  
  class MyList(List[int]):
      def total(self) -&gt; int:
          return sum(i for i in self)
  
  a = MyList([1,2,3])
  print(f'{a.total()=:}')
  </code></pre>
  <p>When I run it, it works</p>
  <pre><code>a.total()=6
  </code></pre>
  <p>But when I use pylint, I get the following error</p>
  <pre><code>...
  toy.py:5:30: E1133: Non-iterable value self is used in an iterating context (not-an-iterable)
  ...
  </code></pre>
  <p>There are other pylint errors, but they're understandable. For the <code>not-an-iterable</code> problem, I don't quite understand it, am I subclassing <code>List[int]</code>, correctly?</p>
  <p>I'm using Python-3.8, pylint==2.6.0</p>