static void Main(string[] args)
{
GradeBook book = new GradeBook();
book.AddGrade(5);
book.AddGrade(6);
book.AddGrade(3);
book.NameChanged += OnNameChanged;
book.Name = "Chris";
book.Name = "Matt";
Console.WriteLine("Grade list:");
Console.WriteLine(book.ShowGrades());
Console.WriteLine("Average:");
Console.WriteLine(book.CalculateAverage());
Console.WriteLine($"Name is {book.Name}");
book.Name = "Popularny Stefanek";
Console.ReadLine();
}
