proposition: Lemma Zabs_of_nat: forall n, Z.abs (Z.of_nat n) = Z.of_nat n.
proof: Proof. unfold Z.of_nat; intros. destruct n; auto. Qed.
imports: Coq.Classes.Morphisms Coq.Classes.Morphisms_Prop Coq.Bool.Bool Coq.Arith.Arith Coq.micromega.Lia Coq.NArith.NArith Coq.ZArith.ZArith bbv.N_Z_nat_conversions bbv.Nomega