Seleniumでinstagramのフォロワーを取得したい

# coding:utf-8

# コマンドライン引数で指定したinstagramerのフォロワーをSeleniumで取得する
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
import bs4
import pandas as pd

import time
import random
import sys

def main():
    username = sys.argv[1]
    print("start crawling follower of " + username)

    # chromedriverのファイル場所はよしなに書き換えてください
    driver = webdriver.Chrome('./chromedriver')
    driver.get('https://www.instagram.com/accounts/login/?source=auth_switcher')
    time.sleep(2)

    # login
    id = driver.find_element_by_name("username")
    id.send_keys("YOUR USERNAME")
    password = driver.find_element_by_name("password")
    password.send_keys("YOUR PASSWORD")
    password.send_keys(Keys.RETURN)
    time.sleep(3)

    driver.get('https://www.instagram.com/' + username + '/')
    time.sleep(3)
    follower_button = driver.find_elements_by_css_selector("li.Y8-fY")[1]
    follower_button.click()
    time.sleep(3)

    dialog = driver.find_element_by_css_selector("div.isgrP")

    # scroll popup window
    # 2300人ほどのユーザーが取れる
    for i in range(200):
        driver.execute_script("arguments[0].scrollTop = arguments[0].scrollHeight", dialog)
        time.sleep(random.randint(500,1000)/1000)

    page_url = driver.page_source
    soup = bs4.BeautifulSoup(page_url,"lxml")
    elm = soup.find_all("a", {"class": "FPmhX notranslate _0imsa"})
    followers = []
    for e in elm:
        followers.append(e.text)

    df = pd.Series(followers)
    df.to_csv("insta_followers_of_" + username + ".csv")
    print("csv file is created.")
    driver.close()

if __name__ == '__main__':
    main()

python sample.py masami_nagasawa

for i in range(200):
        driver.execute_script("arguments[0].scrollTop = arguments[0].scrollHeight", dialog)
        time.sleep(random.randint(500,1000)/1000)