∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] {G : CategoryTheory.Comonad C} {P Q R : G.Coalgebra}
  (f : P.Hom Q) (g : Q.Hom R),
  CategoryTheory.CategoryStruct.comp P.a (G.map (CategoryTheory.CategoryStruct.comp f.f g.f)) =
    CategoryTheory.CategoryStruct.comp (CategoryTheory.CategoryStruct.comp f.f g.f) R.a