Write a monitor solution for the following problem: Suppose a two-way (north-south), two-lane road contains a long one-lane tunnel. A southbound (or northbound) car can only use the tunnel if there are no oncoming cars in the tunnel. Because of accidents, a signaling system has been installed at the entrances to the tunnel. When a car approaches the tunnel, a sensor notifies the controller computer by calling a function arrive with the cars travel direction (north or south). When a car exits the tunnel, the sensor notifies the controller computer by calling depart with the cars travel direction. The traffic controller sets the signal lights: green means go, and red means stop. Construct an algorithm for controlling the lights such that the y operates correctly even when most cars approach the tunnel from one direction. In the monitor solution, consider using a CVar.broadcast function to release all the waiting cars from the north (or south) at once. In which cases, does this make sense?