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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 plot(self, threshold=None, **kwargs):
 """Plot the instanteneous unit hydrograph. The optional argument allows for defining a threshold of the cumulative sum uf the hydrograph, used to adjust the largest value of the x-axis. It must be a value between zero and one. """

        delays, responses = self.delay_response_series
        pyplot.plot(delays, responses, **kwargs)
        pyplot.xlabel('time')
        pyplot.ylabel('response')
        if threshold is not None:
            threshold = numpy.clip(threshold, 0., 1.)
            cumsum = numpy.cumsum(responses)
            idx = numpy.where(cumsum >= threshold*cumsum[-1])[0][0]
            pyplot.xlim(0., delays[idx])