proposition: Fact list_reif_t X Y (R : X -> Y -> Prop) l : (forall x, In x l -> sig (R x)) -> { f | forall x (Hx : In x l), R x (f x Hx) }.
proof: Proof. apply constructive_dep_choice. Qed.
imports: List Arith Lia Undecidability.Shared.Libs.DLW.Utils(utils_tac utils_list utils_nat fin_base) Undecidability.Shared.Libs.DLW.Vec(pos vec)