proposition: Lemma lastkeyPt A (x : nat) (v : A) : x != 0 -> last_key (x \-> v) = x.
proof: Proof. by rewrite /last_key domPtK /= => ->. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path interval) pcm(options prelude pred finmap rtc seqext useqord uslice uconsec)