使用Spotify API时“解析JSON时出错”

我正在学习Python，我正在尝试使用Spotify web api创建一个播放列表，但得到一个http 400错误：解析json时出错 . 我想这与令牌中的错误变量类型有关，但我很难调试它，因为我无法找到以原始格式查看发布请求的方法 .

通过API发布需要授权，这是我为此创建的脚本：

import requests
import base64
requests.packages.urllib3.disable_warnings()

client_id = 'ID'
client_secret = 'SECRET'
redirect_uri = 'http://spotify.com/'
scope = 'playlist-modify-private playlist-read-private'

def request_token():

    #  1. Your application requests authorization
    auth_url = 'https://accounts.spotify.com/authorize'
    payload = {'client_id': client_id, 'response_type':'code','redirect_uri':redirect_uri}
    auth = requests.get(auth_url,params = payload)
    print '\nPlease go to this url to authorize ', auth.url

    #  2. The user is asked to authorize access within the scopes
    #  3. The user is redirected back to your specified URI
    resp_url = raw_input('\nThen please copy-paste the url you where redirected to: ')
    resp_code= resp_url.split("?code=")[1].split("&")[0]

    #  4. Your application requests refresh and access tokens
    token_url = 'https://accounts.spotify.com/api/token'
    payload = {'redirect_uri': redirect_uri,'code': resp_code, 'grant_type': 'authorization_code','scope':scope}
    auth_header = base64.b64encode(client_id + ':' + client_secret)
    headers = {'Authorization': 'Basic %s' % auth_header}
    req = requests.post(token_url, data=payload, headers=headers, verify=True)
    response = req.json()

    return response

这是实际尝试使用授权令牌创建播放列表的功能（导入授权器是上面的功能）：

import requests
import authorizer

def create_playlist(username, list_name):
    token = authorizer.request_token()
    access_token = token['access_token']
    auth_header = {'Authorization': 'Bearer {token}'.format(token=access_token), 'Content-Type': 'application/json'}
    api_url = 'https://api.spotify.com/v1/users/%s/playlists' % username
    payload = {'name': list_name, 'public': 'false'}
    r = requests.post(api_url, params=payload, headers=auth_header)

但无论我尝试什么，它只会导致400错误 . 有人可以在这里指出我的错误吗？