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

Lemma natToWord_discriminate: forall sz, (sz > 0)%nat -> natToWord sz 0 <> natToWord sz 1.