Intructions: All classes in the Event Bus realize the 'Subject' interface.

All classes in the GUI$/$Display box realize the 'Observer' and 'Display' interfaces.

$1.$ Add classes to the Event Bus box that will handle events for Loans and Reservations.

$2.$ Add classes to the GUI$/$Display box that will handle the User Interface for the Loans and Reservations.

$3.$ Explain $($either directly in the diagram or separately$)$ how the Reservation Screen$/$UI knows what to do when a reserved item is loaned out on the Loan Screen$/$UI$.$

GUI $/$ Displays

Event Aggregator $/$ Event Bus