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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def dict_delta(old, new):
 """Return a dictionary containing the items of ``new`` that are either absent from ``old`` or whose values are different; as well as the value ``None`` for those keys that are present in ``old``, but absent from ``new``. Useful for describing changes between two versions of a dict. """

    r = {}
    oldkeys = set(old.keys())
    newkeys = set(new.keys())
    r.update((k, new[k]) for k in newkeys.difference(oldkeys))
    r.update((k, None) for k in oldkeys.difference(newkeys))
    for k in oldkeys.intersection(newkeys):
        if old[k] != new[k]:
            r[k] = new[k]
    return r