from weakref import ref, WeakKeyDictionary, WeakValueDictionary
 
class Id:
    def __init__(self, key):
        self._id = id(key)
        self.keyref = ref(key)
    def __hash__(self):
        return self._id
    def __eq__(self, other):
        return self._id == other._id and self.keyref() is other.keyref()
 
class WeakUnhashableKeyDictionary:
    def __init__(self, *args, **kwargs):
        # TODO Do something to initialize given args and kwargs.
        self.keys = WeakValueDictionary()
        self.values = WeakKeyDictionary()
 
    def __getitem__(self, key):
        return self.values.__getitem__(Id(key))
 
    def __setitem__(self, key, value):
        _id = Id(key)
        # NOTE This works because key holds on _id iif key exists,
        # and _id holds on value iif _id exists. Transitivity. QED.
        # Because key is only stored as a value, it does not need to be hashable.
        self.keys.__setitem__(_id, key)
        self.values.__setitem__(_id, value)
 
    def __delitem__(self, key):
        self.keys.__delitem__(Id(key))
        self.values.__delitem__(Id(key))
 
class Key:
    __hash__ = None
 
d = WeakUnhashableKeyDictionary()
l = [Key(), Key(), Key()]
d[l[0]] = 1
d[l[1]] = 2
 
for k in d.keys.values():
    l.remove(k)
    try:
        print(d[Key()])
        print('False match detected!')
    except KeyError:
        pass

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