Ltac wlt_ind :=
  match goal with
  | [ |- forall (n: word ?len), ?P ] =>
    refine (well_founded_ind (@wlt_wf len) (fun n => P) _)
  end.

Lemma wordToNat_sext_modulo: forall sz (w: word sz) n, Nat.modulo (wordToNat (sext w n)) (pow2 sz) = wordToNat w.