. exact fun ⟨i,hi,hxi⟩ => ⟨⟨i, x.size_eq.symm ▸ hi⟩, hxi⟩
case mp
α : Type u
inst✝ : DecidableEq α
n : Nat
a : α
x : SizedArray α n
⊢ (∃ i hi, x.val[i] = a) → ∃ i, x[↑i] = a

case mpr
α : Type u
inst✝ : DecidableEq α
n : Nat
a : α
x : SizedArray α n
⊢ (∃ i, x[↑i] = a) → ∃ i hi, x.val[i] = a
case mpr
α : Type u
inst✝ : DecidableEq α
n : Nat
a : α
x : SizedArray α n
⊢ (∃ i, x[↑i] = a) → ∃ i hi, x.val[i] = a