Spring Breaks $$R$$ Us $($SBRU$),$ introduced in Assignment $1,$ includes many use cases that make up the functional requirements. Consider the following description of the Booking subsystem. A few weeks before Thanksgiving break, it is time to open the system to new bookings. Students usually want to browse through the resorts and do some planning. After that, when a student or group of students wants to book a trip, the system allows it$.$ Sometimes, a student needs to be added or dropped from the group, or a group changes size and needs a different type of room. One month before the actual trip, it is time for the system to send out final payment requirement notices. Students cancel the booking or they pay their final bills. Students often want to look up their booking status and check on resort details. When they arrive at the resort, they need to check in; and when they leave, they need to check out.