private static void Example2()
{
Chapter c1 = new Chapter(10, "OO");
Chapter c2 = new Chapter(20, "Abstraction");
c1.AddPublication(c2);
Section s1 = new Section(1, "Constructors");
Section s2 = new Section(2, "Visibility");
c2.AddPublication(s1);
c2.AddPublication(s2);
Chapter c3 = new Chapter(20, "Relationships");
c1.AddPublication(c3);
Section s3 = new Section(3, "Associations");
c3.AddPublication(s3);
Console.WriteLine($"{c1.Title}[{c1.TotalPages()}]");
Console.WriteLine($"|--{c2.Title}[{c2.TotalPages()}]");
Console.WriteLine($"|--|--{s1.Title}[{s1.TotalPages()}]");
Console.WriteLine($"|--|--{s2.Title}[{s2.TotalPages()}]");
Console.WriteLine($"|---{c3.Title}[{c3.TotalPages()}]");
Console.WriteLine($"|--|--{s3.Title}[{s3.TotalPages()}]");
}