Consider a traffic light system at a four-way crossroads (two roads intersecting at right angles) with a countdown timer, a crosswalk button, and a speaker that announces it's ok or not ok to walk. This crossroad description is similar to the crossroad on 16^th and Wisconsin Ave at Marquette. Assume the simplest algorithm for cycling through the lights (e.g. all traffic on one road is allowed to go through the crossroad, while the other traffic is stopped. You do not have to account for a left turn arrow light. Identify the states of this system and draw a state machine describing them. Remember that each individual traffic light has at least three states (green, yellow, and red).