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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 norm_score(self):
 """Return the normalized score. Equals 1.0 for a z-score of 0, falling to 0.0 for extremely positive or negative values. """

        cdf = (1.0 + math.erf(self.score / math.sqrt(2.0))) / 2.0
        return 1 - 2*math.fabs(0.5 - cdf)