Given this code snippet, what will be printed when the subject's state changes?

Given this code snippet, what will be printed when the subject's state changes?

class Subject:
    def __init__(self):
        self.observers = []
    def add_observer(self, obs):
        self.observers.append(obs)
    def notify_observers(self):
        for obs in self.observers:
            obs.update()

class Observer:
    def update(self):
        print('State changed!')

subject = Subject()
observer = Observer()
subject.add_observer(observer)
subject.notify_observers()