fact: Definition Maybe_join {X} (x : Maybe (Maybe X)) : Maybe X := match x with | Nothing => Nothing | Just Nothing => Nothing | Just (Just x') => Just x' end.
imports: Category.Lib Category.Theory.Coq.Functor Category.Theory.Coq.Applicative Category.Theory.Coq.Monad Category.Theory.Coq.Semigroup Category.Theory.Coq.Monoid Category.Theory.Coq.Traversable