proposition: Lemma undefE : nm_undef = to (@UM.Undef nat_ordType nat_pred A).
proof: Proof. by []. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path interval) pcm(options prelude pred finmap rtc seqext useqord uslice uconsec)