intro n (ih : step n ≄ n)
ℕ : Type
inst✝¹ : Core ℕ
inst✝ : Induction ℕ
n : ℕ
⊢ ∀ (m : ℕ), step m ≄ m → step (step m) ≄ step m
ℕ : Type
inst✝¹ : Core ℕ
inst✝ : Induction ℕ
n✝ n : ℕ
ih : step n ≄ n
⊢ step (step n) ≄ step n