code: def _se_all(self):
          
          x = np.atleast_2d(self.x)
          err = np.atleast_1d(self.ms_err)
          se = np.sqrt(np.diagonal(np.linalg.inv(x.T @ x)) * err[:, None])
          return np.squeeze(se)
docs: Standard errors (SE) for all parameters, including the intercept.