You're not the one who needs to be convinced ;-)

Please do conduct your own API tests and report back.  

This is necessary for a new class like TransformDict 

that was constructed from scratch and proposed for 

direct admission to the standard library.

This contrasts with other tools like OrderedDict, ChainMap, 

and namedtuple which started their lives outside the standard

library where we we able observe their fitness for real problems

being solved by real users.

None of my consulting client's have anything like a general

purpose transforming dict in their utility modules, so we lack

the real world experience that informed the design of the other

tools in the collections module.  To make up for that lack of

information, we need to put it in front of users as well as 

do research into how other languages have tackled the use cases.

In short, we need to know whether the API will make sense to people,

whether their code will be more readable with a TransformDict,

and whether the zoo of dict variants should continue to grow.

Right now, I don't know those things.  All I have to go on is that

I personally think the TransformDict is a cool idea.  However, that

alone isn't sufficient for accepting the PEP.

Raymond