OAuth Client to refresh access token with caching

simple_oauth.py

import json
import requests
from time import time

class OAuthClient:

    def __init__(self, server, client_id, client_secret, grant_type, scope):
        self.server = server
        self.client_id = client_id
        self.client_secret = client_secret
        self.grant_type = grant_type
        self.scope = scope
        self.expires_on = 0
        self._access_token = None

    def get_access_token(self):
        if time() < self.expires_on:
            print('returning cached token')
            return self._access_token
        body = {
            'grant_type': self.grant_type,
            'client_id': self.client_id,
            'client_secret': self.client_secret,
            'scope': self.scope,
        }
        response = requests.post(self.server, data=body)
        response_json = json.loads(response.content.decode('utf8'))
        access_token = response_json.get('access_token')
        self._access_token = access_token
        expires_in = response_json.get('expires_in')
        self.expires_on = time() + expires_in
        return access_token

if __name__ == '__main__':
    body = { 'grant_type': 'client_credentials',
    'client_id': '1234567890',
    'client_secret': 'XXXXXXXXXXXXXX',
    'scope': 'https://api.example.com/default',
    'server': 'https://login.example.com/oauth2/v2.0/token',
    }
    client = OAuthClient(**body)
    print(client.get_access_token())