proposition: Lemma permutation_length {A: Type}: forall (l1 l2 : list A), Permutation l1 l2 -> Datatypes.length l1 = Datatypes.length l2.
proof: Proof. intros. induction H; simpl; congruence. Qed.
imports: Fiat.Narcissus.Examples.NetworkStack.IPv4Header Fiat.Narcissus.Examples.NetworkStack.TCP_Packet Bedrock.Word Coq.Arith.Arith Coq.Lists.List Fiat.QueryStructure.Automation.MasterPlan IndexedEnsembles Fiat.Narcissus.Examples.Guard.Core Fiat.Narcissus.Examples.Guard.IPTables Fiat.Narcissus.Examples.Guard.PacketFiltersLemmas Fiat.Narcissus.Examples.Guard.DropFields Coq.Sets.Ensembles