Instance enumT_nat : enumT nat.

(* Specifications: *)
Lemma count_nat : enumerable__T nat.
Lemma T_nat_in n m : m <= n -> m el L_T nat n.
Lemma T_nat_length n : length (L_T nat n) = S n.
Lemma T_prod_cum : cumulative T_prod.
Lemma T_prod_el LX LY (a : X * Y) : exists n, a el T_prod LX LY n.