urllib2返回浏览器的不同页面？

import urllib2

response = urllib2.urlopen('http://www.example.com')
html = response.read()

import urllib
import urllib2

url = 'http://www.example.com/login'
data = {'username': 'admin', 'password': '123456'}
data = urllib.urlencode(data)
request = urllib2.Request(url, data)
response = urllib2.urlopen(request)
html = response.read()

import urllib2

url = 'http://www.example.com'
request = urllib2.Request(url)
request.add_header('User-Agent', 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.3')
response = urllib2.urlopen(request)
html = response.read()

import urllib2

response = urllib2.urlopen('http://www.example.com')
status_code = response.getcode()
headers = response.info()
html = response.read()