proposition: Fact ffun_mul_addr : right_distributive ffun_mul (@ffun_add _ _).
proof: Proof. by move=> f1 f2 f3; apply/ffunP=> i; rewrite !ffunE mulrDr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)