public static void PeopleCollectionEnumerationExample() { PeopleCollection people = new PeopleCollection(); people.AddPerson(new Person() { Name = "Mike", Age = 22 }); people.AddPerson(new Person() { Name = "Kate", Age = 17 }); people.AddPerson(new Person() { Name = "John", Age = 20 }); Console.WriteLine("All people"); foreach (Person person in people) Console.WriteLine(person); Console.WriteLine("\r\nUnder age people"); foreach (Person person in people.GetUnderAgePeople()) Console.WriteLine(person); Console.WriteLine("\r\nTake people until under aged"); foreach(Person person in people.GetPeopleUntilUnderAged()) Console.WriteLine(person); }