[2pt] Add all methods visible in the diagram and implement them (Group Task).

[devMunyi]

can_be_archived?() in the Item class

• should return true if published_date is older than 10 years
• otherwise, it should return false

move_to_archive() in the Item class

• should reuse can_be_archived?() method
• should change the archived property to true if the result of the can_be_archived?() method is true
• should do nothing if the result of the can_be_archived?() method is false