intro n₂ (_ : step n₁ ≃ step n₂)
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
n₁✝ n₂✝ m n₁ : ℕ
ih : ∀ (y : ℕ), n₁ ≃ y → n₁ * m ≃ y * m
n₂ : ℕ
⊢ ∀ (m_1 : ℕ), step n₁ ≃ step m_1 → step n₁ * m ≃ step m_1 * m
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
n₁✝ n₂✝¹ m n₁ : ℕ
ih : ∀ (y : ℕ), n₁ ≃ y → n₁ * m ≃ y * m
n₂✝ n₂ : ℕ
x✝ : step n₁ ≃ step n₂
⊢ step n₁ * m ≃ step n₂ * m