proposition: Fact comp_is_semi_additive : semi_additive (f \o h).
proof: Proof. by split=> [|x y]; rewrite /= ?raddf0// !raddfD. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)