theorem extracted_formal_statement_49.{w, v, u} {Z : Type w} {ι : Type v} {f : ι → Z → ℝ} {Ω : Type u}
  [inst : MeasurableSpace Ω] {X : Ω → Z} [inst_1 : Countable ι] (h𝓕 : ∀ (I : ι), Measurable (f I ∘ X)) {n : ℕ} {I : ι}
  {i : Fin n} (h_original_goal : Measurable fun a => f I (X (a i).2)) : Measurable fun a => (a i).2 := sorry

State before:
case hg
Z : Type w
ι : Type v
f : ι → Z → ℝ
Ω : Type u
inst✝¹ : MeasurableSpace Ω
X : Ω → Z
inst✝ : Countable ι
h𝓕 : ∀ (I : ι), Measurable (f I ∘ X)
n : ℕ
I : ι
i : Fin n
⊢ Measurable fun a => f I (X (a i).2)

Tactic: apply (h𝓕 I).comp

State after:
[case hg
 Z : Type w
 ι : Type v
 f : ι → Z → ℝ
 Ω : Type u
 inst✝¹ : MeasurableSpace Ω
 X : Ω → Z
 inst✝ : Countable ι
 h𝓕 : ∀ (I : ι), Measurable (f I ∘ X)
 n : ℕ
 I : ι
 i : Fin n
 ⊢ Measurable fun a => (a i).2]

Relevant lemmas: