proposition: Lemma lreg_neq0 x : lreg x -> x != 0.
proof: Proof. by move=> reg_x; rewrite -[x]mulr1 mulrI_eq0 ?oner_eq0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)