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