static void Main(string[] args)
{
SealClass sc = new SealClass();
sc.Test1(); sc.Test2(); sc.Test3();
int i = 5;
var facti = i.Factorial();
Console.WriteLine(facti);
string str = "sElamat daTanG kE mElAka";
str.toProper();
Console.WriteLine(str);
Console.WriteLine("Hello World!");
}
public static void Test3(this SealClass x)
{
Console.WriteLine("Test Ext Class 3");
}