show from_prod (1 * n + 0 * m, 1 * m + 0 * n) ≃ from_prod (n, m)
ℕ : Type
inst✝ : Natural ℕ
n m : ℕ
⊢ (1 * n + 0 * m)——(1 * m + 0 * n) ≃ n——m
ℕ : Type
inst✝ : Natural ℕ
n m : ℕ
⊢ from_prod (1 * n + 0 * m, 1 * m + 0 * n) ≃ from_prod (n, m)