我不明白count的值是怎么随着实例数量增加的，从这些代码里看不出来
class Person(object):
count = 0
def __init__(self, name):
Person.count = Person.count + 1
self.name = name
p1 = Person('Bob')
print Person.count# => 1p2 = Person('Alice')
print Person.count# => 2p3 = Person('Tim')
print Person.count# => 3
