优先编写Python 3：Twitter错误

Question

我正在使用Python 3

我是一个初学者，正在尝试学习编程。我正在使用Paul Barry和David Griffiths撰写的《 Head First Programming》这本书。 因此，在第3章第92-98页的某处，该书指示编写一个程序，以便经理将直接通过其Twitter帐户将产品价格或购买时间发送给经理。

这是我使用的代码，与书中的代码相同：

import urllib.request
import time


def send_to_twitter(msg):
    password_manager = urllib.request.HTTPPasswordMgr()
    password_manager.add_password("Twitter API",
    "http://twitter.com/statuses", "username", "password")
    http_handler = urllib.request.HTTPBasicAuthHandler(password_manager)
    page_opener = urllib.request.build_opener(http_handler)
    urllib.request.install_opener(page_opener)
    params = urllib.parse.urlencode( {'status': msg} )
    resp = urllib.request.urlopen("http://twitter.com/statuses/update.json", params)
    resp.read()
def get_price():
    page = urllib.request.urlopen("http://beans-r-us.appspot.com/prices.html")
    text = page.read().decode("utf8")
    where = text.find('>$')
    start_of_price = where + 2
    end_of_price = start_of_price + 4
    return float(text[start_of_price:end_of_price])
price_now = input("Do you want to see the price now (Y/N)? ")
if price_now == "Y":
    send_to_twitter(get_price())
else:
    price = 99.99
    while price > 4.74:
        time.sleep(900)
        price = get_price()
send_to_twitter("Buy!")

在用户名和密码部分，我使用了自己的Twitter帐户，但我当然不能在此处显示它。

所以输入错误后发生的事情是：

Do you want to see the price now (Y/N)? Y

   Traceback (most recent call last):
  File "C:\Users\BEST\Desktop\python\headfirsttrychapter3.5.py", line 24, in <module>
    send_to_twitter(get_price())
  File "C:\Users\BEST\Desktop\python\headfirsttrychapter3.5.py", line 13, in send_to_twitter
    resp = urllib.request.urlopen("http://twitter.com/statuses/update.json", params)
  File "C:\Users\BEST\AppData\Local\Programs\Python\Python37\lib\urllib\request.py", line 222, in urlopen
    return opener.open(url, data, timeout)
  File "C:\Users\BEST\AppData\Local\Programs\Python\Python37\lib\urllib\request.py", line 523, in open
    req = meth(req)
  File "C:\Users\BEST\AppData\Local\Programs\Python\Python37\lib\urllib\request.py", line 1247, in do_request_
    raise TypeError(msg)
TypeError: POST data should be bytes, an iterable of bytes, or a file object. It cannot be of type str.

为什么会这样？我该如何解决呢？ :(非常感谢