title: Registration and scope of unittest addTypeEqualityFunc()
body: <p>Python's <code>unittest</code> framework defines the <a href="https://docs.python.org/3.6/library/unittest.html#unittest.TestCase.addTypeEqualityFunc" rel="nofollow noreferrer"><code>addTypeEqualityFunc</code></a> method, which "Registers a type-specific method called by assertEqual() to check if two objects of exactly the same typeobj (not subclasses) compare equal."</p>
  
  <p>What are the scope an mechanism of this registration? The documentation does not discuss either, and "python registration" is resistant to searching. </p>
  
  <p>Mostly, I am curious about whether this "registration" is some kind of assignment in local scope, or if Python has a broader concept of registration I haven't been able to unearth in the docs. </p>