gistfile1.py

import collections, types

class frozendict(collections.UserDict):
    def __init__(self, d=None, **kw):
        d = kw if d is None else dict(d, **kw)
        self.data = types.MappingProxyType(d)
        self._h = sum(map(hash, self.data.items()))

    __hash__ = lambda self: self._h
    __repr__ = lambda self: repr(dict(self))