proposition: Lemma equivfE x y : equivf x y = equivf_notation x y.
proof: Proof. by []. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(ssrAC choice tuple bigop ssralg poly polydiv) mathcomp(generic_quotient)