static void Main()
{
ConcreteColleague1 c1 = new ConcreteColleague1();
ConcreteColleague2 c2 = new ConcreteColleague2();
c1.SetColleague(c2);
c2.SetColleague(c1);
c1.Send("How are you?");
c2.Send("Fine, thanks");
Console.ReadKey();
}
