proposition: Lemma dom_map0 : dom_map (Unit : U) = Unit.
proof: Proof. by rewrite /dom_map omap0. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)