Why is dictionary.keys() a list and not a set?

[Christoph Zwerschke]

Mike Meyer schrieb:

> If the hash changes, you've screwed up the set. What it really should
> say is "collection of objects with fixed hashes", or words to that
> effect. Do you want to file a PR on this?

I fear I have not enough understanding of Python's hashing concepts to 
make a suggestion for improvement here.

> How so? As I demonstrated, you can subclass any class that doesn't
> have a hash to add one, and then use the subclass, which - except for
> having a hash - will have exactly the same behavior as your original
> class.

But you surely wouldn't want to do this to the list of items just to be 
able to return it as a set.

-- Christoph