∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] (X : CategoryTheory.Limits.FormalCoproduct C) (i : X.I),
  CategoryTheory.CategoryStruct.comp ((CategoryTheory.Limits.FormalCoproduct.cofan X.I X.toFun).inj i)
      X.cofanPtIsoSelf.hom =
    CategoryTheory.Limits.FormalCoproduct.Hom.fromIncl i (CategoryTheory.CategoryStruct.id (X.obj i))