proposition: Lemma In_look_up': forall l k v, look_up l k = Some v -> In (k, v) l.
proof: Proof. induction l; intros; simpl in *. 1: inversion H. destruct a as [k' v']. destruct (equiv_dec k' k); unfold equiv in *. - inversion H. subst. now left. - apply IHl in H. now right. 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