proposition: Fact ffun_mul_0r : right_zero (@ffun_zero _ _) ffun_mul.
proof: Proof. by move=> f; apply/ffunP=> i; rewrite !ffunE mulr0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)