Why operations between dict views return a set and not a frozenset?

[Marco Sulla]

On Tue, 4 Jan 2022 at 19:38, Chris Angelico <rosuav at gmail.com> wrote:
> [...] should the keys view be considered
> frozen or not? Remember the set of keys can change (when the
> underlying dict changes).

Well, also the items can change, but they are returned as tuples with
2 elements.

It seems to me that the stdlib, when something should return a
sequence, prefers to return a tuple. So I expected the same preference
for frozenset over set.

> It's not difficult to construct a frozenset from a set.

This sentence has the commutative property :)