proposition: Lemma last_error_cons: forall {A:Type} (l: list A) (a: A), l <> nil -> last_error (a::l) = last_error l.
proof: Proof. intros. destruct l. contradiction. simpl. reflexivity. 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