proposition: Lemma setf_get V (f : {fmap K -> V}) (k : domf f) : f.[val k <- f k] = f.
proof: Proof. by apply/fmapP=> k'; rewrite fnd_set Some_fnd; case: eqP => [->|]. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop)