proposition: Lemma In_domY k f : k \in dom f -> sigT (fun v => (k, v) \In f).
proof: Proof. by case: dom_find=>// v /In_find; exists v. Qed.
imports: Coq(ssreflect ssrbool ssrfun) mathcomp(ssrnat eqtype seq path bigop) pcm(options prelude finmap seqperm pred seqext) pcm(pcm morphism)