proposition: Lemma upd_eta2 k v f : k \notin dom f -> upd k v f = pts k v \+ f.
proof: Proof. by move=>D; rewrite upd_eta freeND. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)