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

Lemma wordToNat_wlshift: forall sz (w: word sz) n, wordToNat (wlshift w n) = Nat.mul (Nat.modulo (wordToNat w) (pow2 (sz - n))) (pow2 n).