proposition: Lemma gcdz_modl m n : gcdz (m %% n)%Z n = gcdz m n.
proof: Proof. by rewrite -!(gcdzC n) gcdz_modr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div choice fintype tuple finfun bigop prime order) mathcomp(ssralg poly ssrnum ssrint archimedean rat matrix) mathcomp(polydiv perm zmodp mxalgebra vector)