Index Exchange interview question

We have a data type called an integer store object, with a name called S. Write 3 functions: a function that takes in parameter S which will allow a user to create an integer store object, a function that takes in parameter S that will allow the user to check whether the integer store object exists (returns type bool), and a function that returns the list of the objects in the order they were inserted (function takes no argument). Use any language you wish.