intuition.
simpl.
unfold indicator.
rewrite H.
repeat rewrite ratMult_0_l.
intuition.
Qed.

(* Specifications: *)
Theorem repeat_snd_equiv :
forall (A B : Set)(eqd : EqDec B)(c : Comp (A * B))(P : B -> bool) x,
evalDist (p <-$ Repeat c (fun p => P (snd p)); ret (snd p)) x ==
evalDist (Repeat (p <-$ c; ret (snd p)) P) x.