Create the persistence layer

This is not used anywhere, make it *private*. Always favor *private* methods.
They are an invitation to refactor when needed because they make it clear it is not being used anywhere else than the current class.

*Public* studd means a contract: "I will keep this working no matter what." Which is not a good contract to have without needing, right?! :wink: 

PS: For someone who didn't knew what to do, you turn out pretty well. :clap: