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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 get_changed(self, p1, p2):
 """ Return the loci that are in clusters that have changed between partitions p1 and p2 """

        if p1 is None or p2 is None:
            return list(range(len(self.insts)))
        return set(flatten_list(set(p1) - set(p2)))