exact ⟨i,hi⟩
case mp.refl
α : Type u
inst✝ : DecidableEq α
a : α
as : Array α
h✝ : ∃ x, (∃ n, List.get as.data n = x) ∧ decide (a = x) = true
i : Fin (List.length as.data)
hi : List.get as.data i = a
h : decide (a = a) = true
⊢ ∃ n, List.get as.data n = a
no goals