proposition: Fact pair_scaleA a b u : scale_pair a (scale_pair b u) = scale_pair (a * b) u.
proof: Proof. by congr (_, _); apply: scalerA. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)