For today's challenge we are going to act as librarians that are trying to keep track of our books.

First, we need to clone the repository and then run irb in the terminal.

1. Create a Book class (in a file called book.rb) so that we can track how many copies of a book we have and whether we have personally finished reading it or not.

   • The Book class should have title, author, finished, and count instance variables.
   • You should be able to pass in the title and author values when you instantiate a book, but only those two attributes.
     • Example: Book.new("Practical Object-Oriented Design in Ruby", "Sandi Metz").
   • finished is a boolean and should default to false.
   • count is an integer and should default to 3.
   • All of the instance variables should be set in the initialize method.

2. Test out your book class using irb.

3. Use attr_ macros to provide access to the instance variables.

   • title and author should only be readable.
   • finished should only be writeable.
   • count should be readable and writeable.

4. Create AudioBook (audio_book.rb) and ComicBook (comic_book.rb) classes that inherit from Book.

   • Add a listen method to AudioBook that sets the finished value to true.
   • Add a read method to ComicBook that sets the finished value to true

5. Add a recommended_books class method to the Book class that creates and returns an array of recommended books

   • Add the following code inside of the recommended_books class method:

  [
    Book.new("The Well-Grounded Rubyist", "David A. Black"),
    Book.new("Practical Object-Oriented Design in Ruby", "Sandi Metz"),
    Book.new("Effective Testing with RSpec 3", "Myron Marston"),
  ]

• Test out the recommended_books class method

6. Create a Lendable module with a lend method that decrements the current count by one.

   • Prevent the count from going below 0 in the lend method
   • Mixin the module into Book
   • Test that you can lend a book by verifying the count has reduced