[1pt] Implement methods - M1

[Daphineatim]

Implement

• add_item method in the Label 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)
• can_be_archived?() in the Book class should override the method from the parent class, should return true if parent's method returns true OR if cover_state equals to "bad" otherwise, it should return false