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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 rollup(self, freq, **kwargs):
 """Downsample `self` through geometric linking. Parameters freq : {'D', 'W', 'M', 'Q', 'A'} The frequency of the result. **kwargs Passed to `self.resample()`. Returns ------- TSeries Example ------- # Derive quarterly returns from monthly returns. 2016-03-31 0.0274 2016-06-30 -0.0032 2016-09-30 -0.0028 2016-12-31 0.0127 Freq: Q-DEC, dtype: float64 """


        return self.ret_rels().resample(freq, **kwargs).prod() - 1.0