Definition rmap_age1 (k:rmap) : option rmap :=
    match unsquash k with
    | (O,_) => None
    | (S n,x) => Some (squash (n,x))
    end.Definition rmap_unage (k:rmap) : rmap :=
    match unsquash k with
    | (n,x) => squash (S n, x)
    end.

Lemma rmap_age1_eq: @age1 _ ag_rmap = rmap_age1.