def hstackarma_minus1(self):
        a = np.concatenate((self.ar[1:], self.ma[1:]),0)
        return a.swapaxes(1,2).reshape(-1, self.nvarall)
stack ar and lagpolynomial vertically in 2d array
dataset/ETHPy150Open statsmodels/statsmodels/statsmodels/tsa/varma_process.py/VarmaPoly.hstackarma_minus1