refine ⟨_,?_,rfl⟩
case intro
n : Nat
α : Type u_1
f : Fin n → α
i : Nat
h : i < size (ofFn f)
⊢ ∃ a, (∃ h, { val := i, isLt := ⋯ } = a) ∧ f a = f { val := i, isLt := ⋯ }
case intro
n : Nat
α : Type u_1
f : Fin n → α
i : Nat
h : i < size (ofFn f)
⊢ ∃ h_1, { val := i, isLt := ⋯ } = { val := i, isLt := ⋯ }