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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 sets(self):
 """Returns the equivalence classes as a set of sets."""

        sets = {}
        for x in self._parents:
            sets.setdefault(self[x], set()).add(x)
        return frozenset(frozenset(v) for v in six.viewvalues(sets))