Identify the error in this Observer pattern code snippet:

Identify the error in this Observer pattern code snippet:

class Subject:
    def __init__(self):
        self.observers = []
    def addObserver(self, observer):
        self.observers.append(observer)
    def notify(self, message):
        for obs in self.observers:
            obs.update()

class Observer:
    def update(self, message):
        print(f"Received: {message}")

s = Subject()
o = Observer()
s.addObserver(o)
s.notify('Test')