proposition: Lemma fnd_set_in V (f : {fmap K -> V}) k0 v0 (x : domf f.[k0 <- v0]) : val x != k0 -> val x \in f.
proof: Proof. by have := valP x; rewrite mem_setf inE; case: eqP. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrnat eqtype ssrfun seq) mathcomp(choice path finset finfun fintype bigop)