python继承和重写init方法

#! /usr/bin/env python
#coding=utf-8

class Dad(object):
def __init__(self, surname ):
self.surname = surname

class Son_1(Dad):
def __init__(self, surname, name ):
Dad.__init__(self, surname)
self.name = name

class Son_2(Dad):
def __init__(self, surname):
Dad.__init__(self, surname)
self.name = 'Si'

if __name__ == '__main__':
son_1 = Son_1('Li', 'Goudan')
print son_1.surname, son_1.name
son_2 = Son_2('Li')
print son_2.surname, son_2.name