proposition: Lemma omf_subdom f h : {subset dom (f h) <= dom h}.
proof: Proof. by case: f=>s [m H] /=; rewrite H; apply: dom_omap_sub. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)