intro n (ih : n * 0 ≃ 0)
ℕ : Type
inst✝⁵ : Core ℕ
inst✝⁴ : Induction ℕ
inst✝³ : Addition ℕ
inst✝² : Sign ℕ
inst✝¹ : Order ℕ
inst✝ : Multiplication ℕ
n : ℕ
⊢ ∀ (m : ℕ), m * 0 ≃ 0 → step m * 0 ≃ 0
ℕ : Type
inst✝⁵ : Core ℕ
inst✝⁴ : Induction ℕ
inst✝³ : Addition ℕ
inst✝² : Sign ℕ
inst✝¹ : Order ℕ
inst✝ : Multiplication ℕ
n✝ n : ℕ
ih : n * 0 ≃ 0
⊢ step n * 0 ≃ 0