proposition: Lemma omf_sorted f h : sorted (@ord K) (dom (f h)).
proof: Proof. by apply: sorted_dom. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)