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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 persist(self, storageLevel):
 """ Persist the RDDs of this DStream with the given storage level """

        self.is_cached = True
        javaStorageLevel = self._sc._getJavaStorageLevel(storageLevel)
        self._jdstream.persist(javaStorageLevel)
        return self