Definition normalize {X} `{Finite X} (d : dist X) : dist X.
refine {|
dist_pmf := map (fun x => (x, eval_dist d (Classes.eqb x))) enum;
dist_law := _;
|}.

Lemma Q_of_nat_prod (x y : nat) :
Q_of_nat (x * y)%nat = Q_of_nat x * Q_of_nat y.