proposition: Lemma ffunK : @cancel (finPi aT rT) fT fun_of_fin finfun.
proof: Proof. by move=> f; apply/ffunP=> x; rewrite ffunE. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype tuple)