Consider the design of an elevator controller. The building has three floors, an up button the first floor, up and down buttons on the second floor, a down button on the third floor, and three buttons inside the elevator indicating the floor to go to. Note that more than one button inside the elevator may have been pressed and active at the same time. While you can make assumptions, the behavior of the system must be reasonable. For example, pressing the “Floor 2” button with the elevator on the second floor causes the elevator to remain there with its door open. Also if the elevator is moving from the second to the third floor, pressing the first floor button inside the elevator should have no effect. -Consider the design of an elevator controller. The building has three floors, an up button on the first floor, up and down buttons on the second floor, a down button on the third floor, and three buttons inside the elevator indicating the floor to go to. Note that more than one button inside the elevator may have been pressed and active at the same time. While you can make assumptions, the behavior of the system must be reasonable. For example, pressing the “Floor 2” button with the elevator on the second floor causes the elevator to remain there with its door open. Also if the elevator is moving from the second to the third floor, pressing the first floor button inside the elevator should have no effect.