[Python-Dev] Add a frozendict builtin type

[Mark Shannon]

Hi,

I don't know if an implementation of the frozendict actually exists,
but if anyone is planning on writing one then can I suggest that they
take a look at my new dict implementation:
http://bugs.python.org/issue13903
https://bitbucket.org/markshannon/cpython_new_dict/

Making dicts immutable (at the C level) is quite easy with my new 
implementation.

Cheers,
Mark.