python login form

import time
from selenium import webdriver

browser = webdriver.Chrome()
wait_time = 1
USER = 'xl.feng'
PWD = 'fengxiaole'
seed_url = 'http://xx.com/login.jhtml'
browser.get(seed_url)
# time.sleep(wait_time)

search_input_user = browser.find_element_by_id('username')
search_input_pwd = browser.find_element_by_id('password')
search_submit = browser.find_element_by_xpath('//div[@class="x-y"]/input[@type="submit"]')

search_input_user.send_keys(USER)
search_input_pwd.send_keys(PWD)

search_submit.click()
time.sleep(wait_time)

new_url = 'http://xx.com/index.jhtml'
browser.get(new_url)
target = browser.find_element_by_xpath('//ul[@class="x-list y-sidebar-list"]/li[3]')
target.click()
target = browser.find_element_by_id('clickHome')
target.click()

new_url = 'http://xx.com/ask/list.jhtml?nxType=nx'
browser.get(new_url)

counter_ = 1

def fun():
    global counter_
    if counter_ == 170000:
        return
    wait_time = 2
    time.sleep(wait_time)

    target = browser.find_element_by_id('dg_next')
    target.click()
    current_url = browser.current_url
    page_source = browser.page_source

    localtime_ = time.strftime("%y%m%d", time.localtime())
    dir_ = 'ml_task_html/'
    filename_ = '%s%s_%s%s' % (dir_, counter_, localtime_, '.html')
    fo = open(filename_, 'w', encoding='utf-8')
    fo.write(page_source)
    fo.closed
    print(counter_)
    counter_ += 1

    fun()

fun()

dd = 0