∀ {B : Type u_1} [inst : TopologicalSpace B] {F₁ : Type u_2} [inst_1 : TopologicalSpace F₁] {E₁ : B → Type u_3}
  [inst_2 : TopologicalSpace (Bundle.TotalSpace F₁ E₁)] {F₂ : Type u_4} [inst_3 : TopologicalSpace F₂]
  {E₂ : B → Type u_5} [inst_4 : TopologicalSpace (Bundle.TotalSpace F₂ E₂)]
  (e₁ : Bundle.Trivialization F₁ Bundle.TotalSpace.proj) (e₂ : Bundle.Trivialization F₂ Bundle.TotalSpace.proj)
  (p : Bundle.TotalSpace (F₁ × F₂) fun x => E₁ x × E₂ x),
  Bundle.Trivialization.Prod.toFun' e₁ e₂ p = (p.proj, (↑e₁ ⟨p.proj, p.snd.1⟩).2, (↑e₂ ⟨p.proj, p.snd.2⟩).2)