intuition.
eapply trans.
eapply refl.
eapply (distro_iso_eq); intros.
eapply H0.
trivial.
eapply H1.
eauto.
eapply H2.
eauto.
eapply H3.
trivial.
eapply eqRat_refl.
eapply rel_seq;
intuition.
Qed.

Theorem evalDist_seq :
forall rel (A1 A2 B : Set) (c1 c2 : Comp B) (f1 : B -> Comp A1)(f2 : B -> Comp A2) y z,
RatRel rel ->
(forall x : B, evalDist c1 x == evalDist c2 x) ->
(forall x : B,
In x (getSupport c1) -> rel (evalDist (f1 x) y) (evalDist (f2 x) z)) ->
rel (evalDist (x <-$ c1; f1 x) y) (evalDist (x <-$ c2; f2 x) z).