{V : Type u} →
  [inst : Quiver V] →
    {motive : Quiver.Arborescence V → Sort u_1} →
      (t : Quiver.Arborescence V) →
        ((root : V) →
            (uniquePath : (b : V) → Unique (Quiver.Path root b)) → motive { root := root, uniquePath := uniquePath }) →
          motive t