proposition: Lemma tuple_of_finfunK : cancel tuple_of_finfun finfun_of_tuple.
proof: Proof. by move=> f; apply/ffunP => i; rewrite ffunE tnth_map tnth_ord_tuple. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype tuple)