intro n (ih : n + 0 ≃ n)
ℕ : Type
inst✝² : Core ℕ
inst✝¹ : Induction ℕ
inst✝ : Addition ℕ
n : ℕ
⊢ ∀ (m : ℕ), m + 0 ≃ m → step m + 0 ≃ step m
ℕ : Type
inst✝² : Core ℕ
inst✝¹ : Induction ℕ
inst✝ : Addition ℕ
n✝ n : ℕ
ih : n + 0 ≃ n
⊢ step n + 0 ≃ step n