proposition: Lemma domeqUf k v f : k \in dom f -> dom_eq (upd k v f) f.
proof: Proof. by rewrite domeq_sym; apply: domeqfU. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)