theorem extracted_formal_statement_54.{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) :
  Measurable fun x => ∑ i, (f I (X (x i).1) - f I (X (x i).2)) := sorry

State before:
case hf.hf
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
c : ι → ℝ
I : ι
⊢ Measurable fun x => ∑ i, (f I (X (x i).1) - f I (X (x i).2))

Tactic: exact measurable_sum_part h𝓕

State after:

Relevant lemmas:
measurable_sum_part : ∀ {Z : Type w} {ι : Type v} {f : ι → Z → ℝ} {Ω : Type u} [inst : MeasurableSpace Ω] {X : Ω → Z}
  [inst_2 : Countable ι],
  (∀ (I : ι), Measurable (f I ∘ X)) → ∀ {n : ℕ} {I : ι}, Measurable fun ω => ∑ i, (f I (X (ω i).1) - f I (X (ω i).2))