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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 compute_cusum_ts(self, ts):
 """ Compute the Cumulative Sum at each point 't' of the time series. """

        mean = np.mean(ts)
        cusums = np.zeros(len(ts))
        cusum[0] = (ts[0] - mean)
        for i in np.arange(1, len(ts)):
            cusums[i] = cusums[i - 1] + (ts[i] - mean)

        assert(np.isclose(cumsum[-1], 0.0))
        return cusums