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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 tracking_error(self, benchmark, ddof=0):
 """Standard deviation of excess returns. The standard deviation of the differences between a portfolio's returns and its benchmark's returns. [Source: CFA Institute] Also known as: tracking risk; active risk Parameters benchmark : {pd.Series, TSeries, 1d np.ndarray} The benchmark security to which `self` is compared. ddof : int, default 0 Degrees of freedom, passed to pd.Series.std(). Returns ------- float """


        er = self.excess_ret(benchmark=benchmark)
        return er.anlzd_stdev(ddof=ddof)