def __init__(self, model, params, normalized_cov_params=None, scale=1.):
        super(ARMAResults, self).__init__(model, params, normalized_cov_params,
                                          scale)
        self.sigma2 = model.sigma2
        nobs = model.nobs
        self.nobs = nobs
        k_exog = model.k_exog
        self.k_exog = k_exog
        k_trend = model.k_trend
        self.k_trend = k_trend
        k_ar = model.k_ar
        self.k_ar = k_ar
        self.n_totobs = len(model.endog)
        k_ma = model.k_ma
        self.k_ma = k_ma
        df_model = k_exog + k_trend * k_ar + k_ma
        self._ic_df_model = df_model + 1
        self.df_model = df_model
        self.df_resid = self.nobs - df_model
        self._cache = resettable_cache()
dataset/ETHPy150Open statsmodels/statsmodels/statsmodels/tsa/arima_model.py/ARMAResults.__init__/operator `+` -> `*`