theorem extracted_formal_statement_252.{u_1, w, u} {Ω : Type u} [inst : MeasurableSpace Ω] {Z : Type w} {n : ℕ}
  {ι : Type u_1} {f : ι → Z → ℝ} [inst_1 : Countable ι] {X : Ω → Z} (hf : ∀ (i : ι), Measurable (f i ∘ X)) (i : ι)
  (k : Fin n) (a : k ∈ Finset.univ) : Measurable fun a => f i (X (a k)) := sorry

State before:
case hf.hf.hf.hg
Ω : Type u
inst✝¹ : MeasurableSpace Ω
Z : Type w
n : ℕ
ι : Type u_1
f : ι → Z → ℝ
inst✝ : Countable ι
X : Ω → Z
hf : ∀ (i : ι), Measurable (f i ∘ X)
ω : Fin n → Ω
i : ι
k : Fin n
a✝ : k ∈ Finset.univ
⊢ Measurable fun a => f i (X (a k))

Tactic: exact measurable_aux0 hf i k

State after:

Relevant lemmas:
measurable_aux0 : ∀ {Ω : Type u} [inst : MeasurableSpace Ω] {Z : Type w} {n : ℕ} {ι : Type u_1} {f : ι → Z → ℝ}
  {X : Ω → Z}, (∀ (i : ι), Measurable (f i ∘ X)) → ∀ (i : ι) (k : Fin n), Measurable fun ω => f i (X (ω k))