在python2中有区别，在Python3中已经没有区别：
object为默认类，表示继承关系
class Person:
name = "zhengtong"
class Animal(object):
name = "chonghong"
if __name__ == "__main__":
x = Person()
print（ "Person", dir(x)）
y = Animal()
print （"Animal", dir(y)）
Python3中运行结果：
person [‘class’, ‘delattr’, ‘dict’, ‘dir’, ‘doc’, ‘eq’, ‘format’, ‘ge’, ‘getattribute’, ‘gt’, ‘hash’, ‘init’, ‘init_subclass’, ‘le’, ‘lt’, ‘module’, ‘ne’, ‘new’, ‘reduce’, ‘reduce_ex’, ‘repr’, ‘setattr’, ‘sizeof’, ‘str’, ‘subclasshook’, ‘weakref’, ‘name’]
animal [‘class’, ‘delattr’, ‘dict’, ‘dir’, ‘doc’, ‘eq’, ‘format’, ‘ge’, ‘getattribute’, ‘gt’, ‘hash’, ‘init’, ‘init_subclass’, ‘le’, ‘lt’, ‘module’, ‘ne’, ‘new’, ‘reduce’, ‘reduce_ex’, ‘repr’, ‘setattr’, ‘sizeof’, ‘str’, ‘subclasshook’, ‘weakref’, ‘name’]