proposition: Lemma scale_is_scalable : scalable ( *:%R b : V -> V).
proof: Proof. by move=> a v /=; rewrite !scalerA mulrC. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)