static void Main()
{
int x = 10;
Console.WriteLine(x.Add(5));
string str = "Hi";
Console.WriteLine(str.ConCat("Ext", "Methods"));
Person1 p = new Person1();
p.ShowPer();
string str1 = "This is a string";
Console.WriteLine(str1.All((a) => a != 's'));
}
public static void ShowPer(this Person1 p)
{
Console.WriteLine("Person class extend");
}