为什么我的selenium（python）代码的某些部分在评论代码后会被执行？

Question

我正在尝试使用selenium和python获取Chrome扩展程序评论者的Google+网址链接。我使用的代码如下：

from selenium import webdriver
from selenium.common.exceptions import ElementNotVisibleException, \
    NoSuchElementException
import sys
import time
import traceback

def create_browser(first_page=None):
    #print "Starting"
    browser = webdriver.Chrome('/home/user/ChromeDriver/chromedriver')
    if first_page:
        browser.get(first_page);
    #print "Done."
    return browser

def close_browser(browser):
    browser.close()

def wait_find_elements_by_class_name(driver, name):
    counter = 0
    while counter < 7:
        try:
            elem = driver.find_elements_by_class_name(name)
            break
        except NoSuchElementException:
            time.sleep(1)
            counter += 1
            elem = None
    return elem

def wait_find_element_by_xpath(driver, path):
    counter = 0
    while counter < 7:
        try:
            elem = driver.find_element_by_xpath(path)
            break
        except NoSuchElementException:
            time.sleep(1)
            counter += 1
            elem = None
    return elem

browser = create_browser()
#print 'loaded'
try:
        #print "Fetching URL"
        url = 'https://chrome.google.com/webstore/detail/movies-showtimes/aaaagimjfioddedkjmggbabjgblfdnkd/reviews'
        print url       
        browser.get(url)
        while(1):                       
            passJS = 0
            gPlusLinks = wait_find_elements_by_class_name(browser, 'comment-thread-displayname')            
            #print "Bla"
            for link in gPlusLinks:             
                passJS += 1
                if passJS <= 2:
                    continue
                l = link.get_attribute('href')
                if l != "javascript:void(0)":
                    print l
            '''time.sleep(3)
            try:
                a = wait_find_element_by_xpath(browser, './/a[@class="webstore-eh webstore-ib-Vg"]')
                a.click()
            except ElementNotVisibleException:
                break
            except AttributeError:
                break   
            print "Scrolled and clicked."
            time.sleep(3)   ''' 
except:
    print "'For loop' exception: ", sys.exc_info()[0]
    for tb in traceback.format_tb(sys.exc_info()[2]):
        print tb

print "Done"

我的问题是，当我将第61行的评论部分（time.sleep(3)）取消注释到第70行的time.sleep(3)时，我的程序终止而不打印Google+网址（即print l声明）。但是，在评论该部分后，它会正确打印URL。

任何人都可以解释为什么会发生这种情况，我该如何预防呢？我真的需要代码才能按顺序执行。我能理解代码是多线程的，但事实并非如此。所以我不知道如何解释这个。