[Python-ideas] Make types.MappingProxyType hashable

[Emanuel Barry]

Hello Python-ideas,
While answering a question earlier today, I realized that
types.MappingProxyType is immutable and unhashable. It seems to me that if
all values are hashable (all keys are already guaranteed to be hashable),
then the mappingproxy itself should be hashable. Should I go ahead and make
a patch for this, or is this a bad idea?

Cheers,
-Emanuel