title: dataclass how to edit list
body: <p>I have a dataclass set up like so:</p>
  <pre><code>from dataclasses import dataclass, field
  from typing import List
  
  @dataclass
  class stats:
     foo: List[list] = field(default_factory=list)
  </code></pre>
  <p>I tried to edit the contents of the list by using</p>
  <p><code>stats().foo = [[1], [1]]</code></p>
  <p>This did nothing. How can I change the contents of the list?</p>