{T : Type u₁} →
  [inst : CategoryTheory.Category.{v₁, u₁} T] →
    (X : T × T) →
      CategoryTheory.Functor (CategoryTheory.CostructuredArrow (CategoryTheory.Over.forget X.1) X.2)
        (CategoryTheory.CostructuredArrow (CategoryTheory.Functor.diag T) X)