# Dictionaries

import itertools

class IdDict(dict):

    '''A dict that stores objects by id()'''

    def add(self, *values):

        for value in values: self[id(value)] = value

        return self

    def add_vars(self, vars_): return self.add(*vars_.values())

class MergeDict:

    '''A dict that checks each of several dicts'''

    def __init__(self, *dicts): self.dicts = dicts

    def __getitem__(self, key):

        for dict_ in self.dicts:

            try: return dict_[key]

            except KeyError: pass

        raise # reraise last KeyError