Python 3.7 TypeError：需要一个类似字节的对象，而不是'str'

我有以下两个字符串：

client_id = "id_str"
client_secret = "secret_str"

我必须像这样通过它们：

def getToken(code, client_id, client_secret, redirect_uri):
    body = {
        "grant_type": 'authorization_code',
        "code" : code,
        "redirect_uri": redirect_uri,
        "client_id": client_id,
        "client_secret": client_secret
    }

    encoded = base64.b64encode("{}:{}".format(client_id, client_secret))
    headers = {"Content-Type" : HEADER, "Authorization" : "Basic {}".format(encoded)} 

    post = requests.post(SPOTIFY_URL_TOKEN, params=body, headers=headers)
    return handleToken(json.loads(post.text))

但是当我这样做时，我得到了错误：

    encoded = base64.b64encode("{}:{}".format(client_id, client_secret))
  File "/usr/local/lib/python3.7/base64.py", line 58, in b64encode
    encoded = binascii.b2a_base64(s, newline=False)
TypeError: a bytes-like object is required, not 'str'

如何解决“ Python 3.7”的这种编码/格式？

ps：我看不到此答案的格式{}和编码。

问题来源：stackoverflow