∀ {C : Type u_1} [inst : CategoryTheory.Category.{v, u_1} C] (X : CategoryTheory.SimplicialObject C)
  (n : SimplexCategoryᵒᵖ),
  (SimplicialObject.opFunctorCompOpFunctorIso.hom.app X).app n =
    CategoryTheory.CategoryStruct.comp SimplicialObject.opObjIso.hom SimplicialObject.opObjIso.hom