fact: Parameter eutt_ret : forall (r1 r2 : R), r1 = r2 -> Ret r1 ≈ Ret r2.
imports: Coq(Setoid Morphisms) ITree(Eq.Shallow) ITree.Core.ITreeDefinition ITree.Basics.Basics ITree.Indexed.Sum ITree.Interp.Interp ITree.Interp.Recursion