proposition: Lemma add0_l : left_id 0%:F add.
proof: Proof. elim/quotW=> x; rewrite !piE /addf !numden_Ratio ?oner_eq0 //. by rewrite mul0r mul1r mulr1 add0r Ratio_numden. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(ssrAC choice tuple bigop ssralg poly polydiv) mathcomp(generic_quotient)