- Book: title, author
- Order: book, reader, date
- Reader: name, email, city, street, house
- Author: name, biography
- Library: books, orders, readers, authors
- Who often takes the book
- What is the most popular book
- How many people ordered one of the three most popular books
- Save all Library data to file(s)
- Get all Library data from file(s)
// get all existing data libraries
library = Library.new
// method statistic shows: the best book, the best reader and How many people ordering one of the three most popular books
library.statistic
// method get_all - shows all libraries
library.get_all
// method save_library - save all data to json file
library.save_library
// method add_object- creates any object from instance_class( Book Order Reader Author )
example library.add_object(Author.new("Jerome Salinger", ""))