proposition: Lemma wrshifta_0: forall sz (w: word sz), wrshifta w 0 = w.
proof: Proof. unfold wrshifta; intros; simpl. unfold eq_rec_r, eq_rec. unfold sext. destruct (wmsb w false). - cbn; rewrite combine_n_0. rewrite eq_rect_2; reflexivity. - cbn; rewrite combine_n_0. rewrite eq_rect_2; reflexivity. Qed.
imports: Coq.Classes.Morphisms Coq.Classes.Morphisms_Prop Coq.Classes.Equivalence Coq.Arith.PeanoNat Coq.ZArith.BinInt  Coq.Arith.Arith Coq.NArith.NArith Coq.Bool.Bool Coq.ZArith.ZArith Coq.Logic.Eqdep_dec Coq.Logic.EqdepFacts Coq.Program.Tactics Coq.Program.Equality Coq.setoid_ring.Ring Coq.setoid_ring.Ring_polynom bbv.Nomega bbv.ZLib bbv.NatLib bbv.NLib bbv.N_Z_nat_conversions bbv.DepEq bbv.DepEqNat bbv.ReservedNotations Coq.micromega.Lia