show from_prod (n * m, 0) ≃ from_prod (n * m + 0 * 0, n * 0 + 0 * m)
ℕ : Type
inst✝ : Natural ℕ
n m : ℕ
⊢ (n * m)——0 ≃ (n * m + 0 * 0)——(n * 0 + 0 * m)
ℕ : Type
inst✝ : Natural ℕ
n m : ℕ
⊢ from_prod (n * m, 0) ≃ from_prod (n * m + 0 * 0, n * 0 + 0 * m)