∀ (A : Type u₁) [inst : CategoryTheory.Category.{v₁, u₁} A] (B : Type u₂) [inst_1 : CategoryTheory.Category.{v₂, u₂} B]
  (C : Type u₃) [inst_2 : CategoryTheory.Category.{v₃, u₃} C] (X : CategoryTheory.Functor A (B × C)) (X_1 : A),
  ((CategoryTheory.functorProdFunctorEquivCounitIso A B C).hom.app X).app X_1 =
    CategoryTheory.Prod.mkHom (CategoryTheory.CategoryStruct.id (X.obj X_1).1)
      (CategoryTheory.CategoryStruct.id (X.obj X_1).2)