Graph API with Python

#!/usr/bin/env python
import requests, json

class Facebook:

    app_id, app_secret = ('app-id','app-secret')
    url, token = ('https://graph.facebook.com', None)

    def __init__(self, token=''):
        if token:
            self.token = token
        else:
            self.token = self.get_app_token(self.app_id, self.app_secret)

    def get_app_token(self, app_id, app_secret):
        payload = {'grant_type': 'client_credentials', 'client_id': app_id, 'client_secret': app_secret}
        return requests.post(self.url+'/oauth/access_token?', params = payload).text.split("=")[1]

    def get_user(self, node='me', fields=[]):
        url = self.url+'/%s?access_token=%s&fields=%s' % (node, self.token, ','.join(fields))
        return json.loads(requests.get(url).text)

fb = Facebook()
print(fb.get_user('user-id', ['name','user_birthday','email']))