code: def update(self):
          
          del self.ma.coefs
          del self.arma.ma_coefs
          del self.arma.ar_coefs
          if self.primary_parameters_complete:
              self.calc_secondary_parameters()
          else:
              for secpar in self._SECONDARY_PARAMETERS.values():
                  secpar.__delete__(self)
docs: Delete the coefficients of the pure MA model and also all MA and
          AR coefficients of the ARMA model.  Also calculate or delete the values
          of all secondary iuh parameters, depending on the completeness of the
          values of the primary parameters.