#[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 CR_cv_shift : forall {R : ConstructiveReals} f k l, CR_cv R (fun n => f (n + k)%nat) l -> CR_cv R f l.