proposition: Lemma empty_list_length: forall {A: Type} (a: list A), (length a = 0)%nat <-> a = [].
proof: Proof. intros A a. induction a; split; intros; auto; contradict H; easy. Qed.
imports: Int63 PArray SMT_classes ZArith Misc State SMT_terms BVList Psatz Bool List BoolEq NZParity Nnat BinPos BinNat Pnat Init.Peano ProofIrrelevance