我是一个初学蟒蛇学习者.为什么这段代码不能打印100？
class Pet(object):
def __init__(self):
self.name = ''
self.age = 0
def getName(self, newname):
self.name = newname
return self.name
def getAge(self, aging):
self.age += aging
return self.age
polly = Pet()
polly.getAge(100)
print polly.getAge