proposition: Lemma ptsU k v : pts k v = upd k v Unit :> U.
proof: Proof. by rewrite !pcmE /= !umEX /UM.pts /UM.upd; case: decP. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)