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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 nth(self, n, *args, **kwargs):
 """Take the nth element of each grouby."""

        # TODO: Stop collecting the entire frame for each key.
        self._prep_pandas_groupby()
        myargs = self._myargs
        mykwargs = self._mykwargs
        nthRDD = self._regroup_mergedRDD().mapValues(
            lambda r: r.nth(
                n, *args, **kwargs)).values()
        return DataFrame.fromDataFrameRDD(nthRDD, self.sql_ctx)