proposition: Lemma In_omf f k v h : (k, v) \In f h <-> exists2 w, (k, w) \In h & map_fun f (k, w) = Some v.
proof: Proof. by case: f=>s [m H] /=; rewrite H In_omapX. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)