Seriously, I'm curious: what needs to mature, according to you?
In my mind, its availability on PyPI along with demonstrated use in the wild (plus corresponding votes to demonstrate that people use/like it) would help. That you can find several implementations at this doesn't mean it's necessarily worth adding to the std lib. Once in, it is very difficult to evict something that is later deemed not to have belonged in the std lib, so I think some extra scrutiny is worthwhile. Is there some obvious advantage to having a single API for this available to all Python applications? Are the semantics well-defined (do all the implementations you cited offer basically the same semantics)? The discussion so far here suggest that the best semantics might not be completely settled. (I still don't care for the name. "Transform" != "case folding" in my mind. A quick scan of your links suggests most people think something like "cidict" or "CaseInsensitiveDict" would be more descriptive.) Skip