theorem extracted_formal_statement_63.{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)) :
  Measurable fun a => ∑ σ, ⨆ i, |∑ k, ↑↑(σ k) * f i (X (a.1 k))| := sorry

State before:
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)
⊢ Measurable fun a => ∑ σ, ⨆ i, |∑ k, ↑↑(σ k) * f i (X (a.1 k))|

Tactic: apply measurable_aux20 hf

State after:

Relevant lemmas:
measurable_aux20 : ∀ {Ω : Type u} [inst : MeasurableSpace Ω] {Z : Type w} {n : ℕ} {ι : Type u_1} {f : ι → Z → ℝ}
  [inst_2 : Countable ι] {X : Ω → Z},
  (∀ (i : ι), Measurable (f i ∘ X)) → Measurable fun ω => ∑ σ, ⨆ i, |∑ k, ↑↑(σ k) * f i (X (ω.1 k))|