How to use the tsfresh.feature_extraction.feature_calculators.fft_aggregated function in tsfresh

As in tsfresh `fft_aggregated `_

        Returns the spectral centroid (mean), variance, skew, and kurtosis of the absolute fourier transform spectrum.

        :param x: the time series to calculate the feature of
        :type x: pandas.Series
        :param param: contains dictionaries {"aggtype": s} where s str and in ["centroid", "variance",
            "skew", "kurtosis"]
        :type param: list
        :return: the different feature values
        :rtype: pandas.Series
        """
        if param is None:
            param = [{'aggtype': 'centroid'}]
        _fft_agg = feature_calculators.fft_aggregated(x, param)
        logging.debug("fft aggregated by tsfresh calculated")
        return list(_fft_agg)

def function(x):
            param = [{'aggtype': self.aggtype}]
            return list(fft_aggregated(x, param=param))[0][1]