proposition: Lemma equal_sym_b x y : equal x y = equal y x.
proof: Proof. to_caps; fsetdec. Qed.
imports: Coq.MSets.MSetInterface Coq.MSets.MSetProperties Coq.MSets.MSetFacts Coq.MSets.MSetDecide Fiat.Common.Instances Fiat.Common.BoolFacts Fiat.Common