Fixpoint natToTerm (n : nat) : Term :=
  match n with
  | O => Zero
  | S m => Succ (natToTerm m)
  end.

(* Specifications: *)
Lemma closedNatToTerm : forall a v : nat, ~ In v (freeVarTerm LNN (natToTerm a)).
Lemma closedNatToTerm : forall a v : nat, ~ In v (freeVarTerm LNT (natToTerm a)).