[1.5pt] Create an Author class - student C

[Salimer]

• Create an Author class with an association to the Item class (in a separate .rb file).
• All Author class properties visible in the diagram should be defined and set up in the constructor method.
• Implement the method: add_item method in the Author class
  • should take an instance of the Item class as an input
  • should add the input item to the collection of items
  • should add self as a property of the item object (by using the correct setter from the item object)