A museum allows visitors to enter through the east entrance and leave through its west exit. Arrivals and departures are signalled to the museum controller by the turnstiles at the entrance and exit. At opening time, the museum director signals the controller that the museum is open and then the controller permits both arrivals and departures. At closing time, the director signals that the museum is closed, at which point only departures are permitted by the controller.

For Process Algebra models $($as FSP$),$ the museum system consists of processes EAST, WEST, CONTROL and DIRECTOR.

a$.$Draw the structure diagram for the museum