public static IEnumerable <Stck <A> > Sequence <A>(this Stck <IEnumerable <A> > ta) => ta.Traverse(identity);
public static Eff <RT, Stck <A> > Sequence <RT, A>(this Stck <Eff <RT, A> > ma) where RT : struct => ma.Traverse(identity);
public static Task <Stck <A> > Sequence <A>(this Stck <Task <A> > ma) => ma.Traverse(identity);