proposition: Lemma Npow2_pos: forall a, (0 < Npow2 a)%N.
proof: Proof. intros. destruct (Npow2 a) eqn: E. - exfalso. apply (Npow2_not_zero a). assumption. - constructor. 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