∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] (D : CategoryTheory.GlueData' C) (i : D.J),
  (if h : i = i then CategoryTheory.eqToHom ⋯
    else
      CategoryTheory.CategoryStruct.comp (CategoryTheory.eqToHom ⋯)
        (CategoryTheory.CategoryStruct.comp (D.t i i h) (CategoryTheory.eqToHom ⋯))) =
    CategoryTheory.CategoryStruct.id (if h : (i, i).1 = (i, i).2 then D.U (i, i).1 else D.V (i, i).1 (i, i).2 h)