Ltac prog_assoc_r :=
    eapply comp_spec_eq_trans_r; [ idtac | eapply comp_spec_assoc].(* A bounded repeat based on fold. *)
Definition repeatMax(A : Set)(eqd : EqDec A)(c : Comp A)(P : A -> bool) def (n : nat):=
  compFold _ (fun a' i => if (P a') then (ret a') else c) def (allNatsLt n).

Lemma length_flatten_eq : forall (A B : Set)(lsa : list (list A))(lsb : list (list B)), list_pred (fun a1 a2 => length a1 = length a2) lsa lsb -> length (flatten lsa) = length (flatten lsb).