public class MyBase<K, V>
{
	public class Callback
	{ }

	public void Hello (Callback cb)
	{ }
}

public class X : MyBase<string, int>
{
	public X (Callback cb)
	{ }

	public void Test (Callback cb)
	{
		Hello (cb);
	}

	public static void Main ()
	{ }
}