∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.Limits.HasZeroMorphisms C]
  {X Y : C} (b : CategoryTheory.Limits.BinaryBicone X Y)
  (x : CategoryTheory.Discrete CategoryTheory.Limits.WalkingPair),
  CategoryTheory.CategoryStruct.comp (b.toBicone.toCocone.ι.app x)
      (CategoryTheory.Iso.refl b.toBicone.toCocone.pt).hom =
    b.toCocone.ι.app x