Section eqit_h.
Context {E : Type -> Type} {R1 R2 : Type} (RR : R1 -> R2 -> Prop).
(** [eqit] is a congruence for [itree] constructors. *)

Lemma eqit_Ret b1 b2 (r1 : R1) (r2 : R2) :
RR r1 r2 <-> @eqit E _ _ RR b1 b2 (Ret r1) (Ret r2).