proposition: Lemma app_not_nil: forall {A} (l: list A) (a: A), l ++ (a :: nil) <> nil.
proof: Proof. intros. destruct l; intro; simpl in H; inversion H. Qed.
imports: Coq.Lists.List Coq.micromega.Lia Coq.Sorting.Permutation Coq.ZArith.ZArith_base Coq.ZArith.Zcomplements Coq.Logic.FunctionalExtensionality CertiGraph.lib.Coqlib CertiGraph.lib.EquivDec_ext VST.zlist.sublist VST.zlist.list_solver