∀ {X Y Z : Type u} [inst : PartialOrder X] [inst_1 : PartialOrder Y] [inst_2 : PartialOrder Z] (f : X →o Y)
  (g : Y →o Z), PartOrd.ofHom (g.comp f) = CategoryTheory.CategoryStruct.comp (PartOrd.ofHom f) (PartOrd.ofHom g)