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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 sample(self, withReplacement, fraction, seed=None):
 """ Return a sampled subset of this RDD. :param withReplacement: can elements be sampled multiple times (replaced when sampled out) :param fraction: expected size of the sample as a fraction of this RDD's size without replacement: probability that each element is chosen; fraction must be [0, 1] with replacement: expected number of times each element is chosen; fraction must be >= 0 :param seed: seed for the random number generator .. note:: This is not guaranteed to provide exactly the fraction specified of the total count of the given :class:`DataFrame`. True """

        assert fraction >= 0.0, "Negative fraction value: %s" % fraction
        return self.mapPartitionsWithIndex(RDDSampler(withReplacement, fraction, seed).func, True)