public static void MainTest()
{
var x1 = new X1();
var x2 = new X2();
var x3 = new X3();
var x4 = new X4();
x4.Display2();
x1 = x4;
x1.Display1();
System.Console.WriteLine(x1.y);
//x1.Display2();
System.Console.WriteLine();
var tt = new Y <int, Double>();
tt.Set(3);
tt.Set(.3);
x1 = new X1();
var x11 = new X1();
x2 = new X2();
var x22 = new X2();
x1 = T1.V1(x22);
//x2 = T1.V2(x1);
}