A frozen set is a frozenset.
A frozen list could be a tuple.
What would be a frozen dict ? An immutable, hashable dict.
I guess it could be something like collections.namedtuple, but namedtuple is more like a frozenkeys dict (an half-frozen dict). No ?
Which features of regular expressions are standard, and which are idiosyncratic ?
What should I do, and not do, if I want to use the same regex in different context, languages, platforms ?