Your task for this exercise is to model the state machine diagram for a shopping cart: specifically, for the Cart used in the MyUB course registration process. This includes the logic dictating whether a course can be added to the cart.

Your model needs to include:

1. all states for the cart, including any concurrent states
2. the pseudostate (starting point)
3. All transitions
4. All action-expressions and guard-conditions

The model syntax must comply with the rules given in the text (be UML 2 compliant), and transitions must be named appropriately. The model must also be specific to the registration system, not a generic shopping cart model.