proposition: Lemma id_omf_ax : OmapFun.axiom (@id U) (Some \o snd).
proof: Proof. by move=>f; rewrite omap_some. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)