proposition: Fact comp_is_multiplicative : multiplicative (f \o g).
proof: Proof. by split=> [x y|] /=; rewrite ?rmorph1 ?rmorphM. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)