# Dictionaries

def id_dict(objects=[]):

    '''Makes a dict of objects by id() value'''

    return dict(((id(v), v) for v in objects))

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