python selenium设置chrome的下载路径

python可以通过ChromeOptions设置chrome参数，如下载路径等，代码如下(python 3.6.7)：

#-*-coding=utf-8-*-

from selenium import webdriver
import time

def set_chrome_pref():
    chromeOptions = webdriver.ChromeOptions()
    prefs = {"download.default_directory":"D:\\"}
    chromeOptions.add_experimental_option("prefs", prefs)
    driver = webdriver.Chrome(chrome_options=chromeOptions)
    time.sleep(10)