proposition: Lemma disjoint_one_2 : forall A B (x : atom) (a : A) (F : list (asn A B)), x `notin` dom F -> disjoint (one (VarAsn B x a)) F.
proof: Proof. unfold disjoint. intros. simpl_asnlist in *. fsetdec. Qed.
imports: Coq.FSets.FSets Coq.Lists.List Coq.Logic.Decidable Metalib.CoqFSetDecide Metalib.CoqListFacts Metalib.LibTactics Metalib.MetatheoryAtom Metalib.LibTactics