fact: Definition equiv_pred {A : Type} (R S: A -> Prop): Prop := forall a, R a <-> S a.
imports: Coq(RelationClasses) ExtLib(Structures.Functor Structures.Monad Data.Monads.StateMonad Data.Monads.ReaderMonad Data.Monads.OptionMonad Data.Monads.EitherMonad)