intro n₂
ℕ : Type
inst✝² : Core ℕ
inst✝¹ : Induction ℕ
inst✝ : Addition ℕ
n₁ n₂ m : ℕ
⊢ ∀ (y : ℕ), 0 ≃ y → 0 + m ≃ y + m
ℕ : Type
inst✝² : Core ℕ
inst✝¹ : Induction ℕ
inst✝ : Addition ℕ
n₁ n₂✝ m n₂ : ℕ
⊢ 0 ≃ n₂ → 0 + m ≃ n₂ + m