code: def setDesigns(self, F, A):
          
          F = to_list(F)
          A = to_list(A)
          assert len(A) == len(F), 'MeanKronSum: A and F must have same length!'
          n_terms = len(F)
          n_covs = 0
          k = 0
          l = 0
          for ti in range(n_terms):
              assert F[ti].shape[0] == self._N, 'MeanKronSum: Dimension mismatch'
              assert A[ti].shape[1] == self._P, 'MeanKronSum: Dimension mismatch'
              n_covs += F[ti].shape[1] * A[ti].shape[0]
              k += F[ti].shape[1]
              l += A[ti].shape[0]
          self._n_terms = n_terms
          self._n_covs = n_covs
          self._k = k
          self._l = l
          self._F = F
          self._A = A
          self._b = sp.zeros((n_covs, 1))
          self.clear_cache('predict_in_sample', 'Yres', 'designs')
          self._notify('designs')
          self._notify()
docs: set fixed effect designs