proposition: Lemma eq_dffun (g1 g2 : forall x, rT x) : (forall x, g1 x = g2 x) -> finfun g1 = finfun g2.
proof: Proof. by move=> eq_g; apply/ffunP => x; rewrite !ffunE eq_g. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype tuple)