proposition: Lemma mcoeffB k : {morph mcoeff k: x y / x - y}.
proof: Proof. exact: raddfB. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap