∀ {C : Type u₁} [inst : CategoryTheory.Category.{v₁, u₁} C] {D : Type u₂} [inst_1 : CategoryTheory.Category.{v₂, u₂} D]
  {E : Type u₃} [inst_2 : CategoryTheory.Category.{v₃, u₃} E] (L : CategoryTheory.Functor C D)
  (R : CategoryTheory.Functor E D) (X : E) (X_1 : ↑((R.comp (CategoryTheory.CostructuredArrow.functor L)).obj X)),
  (CategoryTheory.CostructuredArrow.ιCompGrothendieckPrecompFunctorToCommaCompFst L R X).hom.app X_1 =
    CategoryTheory.CategoryStruct.id X_1.left