∀ {C : Type u_1} [inst : CategoryTheory.Category.{u_3, u_1} C] {D : Type u_4}
  [inst_1 : CategoryTheory.Category.{u_2, u_4} D] (F : CategoryTheory.Functor C D) (d : D)
  (X : (CategoryTheory.CostructuredArrow F d)ᵒᵖ),
  CategoryTheory.StructuredArrow.homMk (CategoryTheory.CategoryStruct.id X).unop.left.op ⋯ =
    CategoryTheory.CategoryStruct.id (CategoryTheory.StructuredArrow.mk (Opposite.unop X).hom.op)