class Person(object):
   address = 'Earth'
   def __init__(self, name):
       self.name = name

p1 = Person('Bob')
p2 = Person('Alice')

print 'Person.address = ' + Person.address

p1.address = 'China'
print 'p1.address = ' + p1.address

print 'Person.address = ' + Person.address
print 'p2.address = ' + p2.address

求问  加黑体的代码代表哦什么意思