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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 percentile(self, n, default=None):
 """ Calculate the Nth Percentile value over the time series. :param int n: Integer value of the percentile to calculate. :param default: Value to return as a default should the calculation not be possible. :return: Float representing the Nth percentile value or `None`. """

        return numpy.asscalar(numpy.percentile(self.values, n)) if self.values else default