The Elevator System

There is one button on each floor just outside of the elevator that passengers can press to summon the

elevator to come pick them up$.$ There are multiple buttons inside of the elevator depending on the floors the building has, one button for each floor, that passengers can press to instruct the elevator to deliver them to the associated floor.

When idle, the elevator is stationary at the last floor serviced, with its doors closed. When there is a

request to service a particular floor $($i$.$e$.,$ to deliver a passenger to that floor, or to pick up a passenger from that floor$),$ the elevator moves to that floor $($if necessary$)$ and opens its doors. A request to service a floor remains outstanding until the elevator reaches the requested floor and opens its doors; at which point, all outstanding requests for that floor are considered serviced.

If the elevator is stationary, then requests to service the floor that the elevator is currently on have priority over requests to service the other floor. For simplicity, your model should have only one door for the elevator $($i$.$e$.,$ don$$t model the outside doors on each floor$).$ When the elevator door is opened, it remains open for $5$ seconds. If the door sensors detect some blockage on closing the doors, the doors will reopen and again try to close after $5$ seconds.

Create a state$-$machine diagram for an elevator that has the domain model provided in the scenario.