#[global]
Instance CR_cv_morph
  : forall {R : ConstructiveReals} (un : nat -> CRcarrier R), CMorphisms.Proper
      (CMorphisms.respectful (CReq R) CRelationClasses.iffT) (CR_cv R un).

Lemma Rcv_cauchy_mod : forall {R : ConstructiveReals} (un : nat -> CRcarrier R) (l : CRcarrier R), CR_cv R un l -> CR_cauchy R un.