def prepare_data(self):
        endog, exog = super(SARIMAX, self).prepare_data()

        # Perform simple differencing if requested
        if (self.simple_differencing and
           (self.orig_k_diff > 0 or 0 > self.orig_k_seasonal_diff)):
            # Perform simple differencing
            endog = diff(endog.copy(), self.orig_k_diff,
                         self.orig_k_seasonal_diff, self.k_seasons)
            if exog is not None:
                exog = diff(exog.copy(), self.orig_k_diff,
                            self.orig_k_seasonal_diff, self.k_seasons)

            # Reset the ModelData datasets
            self.data.endog, self.data.exog = (
                self.data._convert_endog_exog(endog, exog))

        # Reset the nobs
        self.nobs = endog.shape[0]

        # Cache the arrays for calculating the intercept from the trend
        # components
        time_trend = np.arange(1, self.nobs + 1)
        self._trend_data = np.zeros((self.nobs, self.k_trend))
        i = 0
        for k in self.polynomial_trend.nonzero()[0]:
            if k == 0:
                self._trend_data[:, i] = np.ones(self.nobs,)
            else:
                self._trend_data[:, i] = time_trend**k
            i += 1

        return endog, exog
dataset/ETHPy150Open statsmodels/statsmodels/statsmodels/tsa/statespace/sarimax.py/SARIMAX.prepare_data/swapped operands of `>`