proposition: Lemma ncons_correct sv st n : RelP sv st -> RelP (ncons n dv sv) (ncons n dt st).
proof: Proof. by move=> Hs k; rewrite !nth_ncons; case: ifP. Qed.
imports: Coq(Rdefinitions Raxioms RIneq Rbasic_fun) mathcomp.ssreflect(ssreflect ssrfun ssrbool eqtype ssrnat seq bigop) MathComp1or2