∀ {α : Type u_3} {l : Type u_9} {m : Type u_10} {n : Type u_11} [inst : MulZeroOneClass α] [inst_1 : DecidableEq n]
  (A : Matrix l m α), Matrix.kroneckerMap (fun x1 x2 => x1 * x2) A 1 = Matrix.blockDiagonal fun x => A