Definition ag_knot : ageable knot :=
    mkAgeable knot def_knot_level def_knot_age1 ag_knot_facts .

(* Specifications: *)
Lemma knot_level : forall k:knot, level k = fst (unsquash k).
Lemma knot_age1 : forall k:knot, age1 k = match unsquash k with | (O,_) => None | (S n,x) => Some (squash (n,x)) end.