∀ (C : Type u_2) [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.Preadditive C]
  (U : CategoryTheory.Comonad C) [U.Additive] (F G : U.Coalgebra),
  CategoryTheory.CategoryStruct.comp F.a (U.map 0) = CategoryTheory.CategoryStruct.comp 0 G.a