∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] [CategoryTheory.Limits.HasZeroMorphisms C] {X Y : C}
  [inst_2 : CategoryTheory.Limits.HasColimit (CategoryTheory.Limits.pair X Y)],
  CategoryTheory.IsSplitMono CategoryTheory.Limits.coprod.inr