1 // CS1961: The covariant type parameter `V' must be invariantly valid on `Both<U,V>(Covariant<None<Contra<V>>>)'
4 delegate T Covariant<out T> ();
5 delegate void Contra<in T> (T t);
6 delegate void None<T> (T t);
8 delegate void Both<in U, out V> (Covariant<None<Contra<V>>> b);