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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 countByValueAndWindow(self, windowDuration, slideDuration, numPartitions=None):
 """ Return a new DStream in which each RDD contains the count of distinct elements in RDDs in a sliding window over this DStream. @param windowDuration: width of the window; must be a multiple of this DStream's batching interval @param slideDuration: sliding interval of the window (i.e., the interval after which the new DStream will generate RDDs); must be a multiple of this DStream's batching interval @param numPartitions: number of partitions of each RDD in the new DStream. """

        keyed = self.map(lambda x: (x, 1))
        counted = keyed.reduceByKeyAndWindow(operator.add, operator.sub,
                                             windowDuration, slideDuration, numPartitions)
        return counted.filter(lambda kv: kv[1] > 0)