intro n₁ (ih : ∀ y, n₁ ≃ y → n₁ + m ≃ y + m) n₂
ℕ : Type
inst✝² : Core ℕ
inst✝¹ : Induction ℕ
inst✝ : Addition ℕ
n₁ n₂ m : ℕ
⊢ ∀ (m_1 : ℕ), (∀ (y : ℕ), m_1 ≃ y → m_1 + m ≃ y + m) → ∀ (y : ℕ), step m_1 ≃ y → step m_1 + m ≃ y + m
ℕ : Type
inst✝² : Core ℕ
inst✝¹ : Induction ℕ
inst✝ : Addition ℕ
n₁✝ n₂✝ m n₁ : ℕ
ih : ∀ (y : ℕ), n₁ ≃ y → n₁ + m ≃ y + m
n₂ : ℕ
⊢ step n₁ ≃ n₂ → step n₁ + m ≃ n₂ + m