proposition: Lemma omf_cond f h x : x \in dom (f h) -> C x.
proof: Proof. by case: f=>s [m H] /=; rewrite H=>/dom_cond. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)