Hi Patrick,

These container classes are not intended to be subclassed at all,
and we never do that in our own applications.

If we added the super() calls, we might possibly break other people's
subclasses that depend (unfortunately) on not calling the next
__init__() in the inheritance tree.    Is it worth this risk?

When we use Mixins in other contexts, we just call the
parent __init__() methods explicitly so that the behavior is
easier to understand.  Would that work as well for you?

And I'm glad you like Durus!  We like it too.

- David