∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] {X Y : C} (S : C)
  [inst_1 : CategoryTheory.CanonicallyOverClass X Y] [inst_2 : CategoryTheory.OverClass Y S],
  X ↘ S = CategoryTheory.CategoryStruct.comp (X ↘ Y) (Y ↘ S)