Simple JSON file cache to retrieve e.g. a token

cached_token.py

import os
import json

def cached_token(jsonfile):
    def has_valid_token(data):
        return 'token' in data

    def get_token_from_file():
        with open(jsonfile) as f:
            data = json.load(f)
            if has_valid_token(data):
                return data.get('token')

    def save_token_to_file(token):
        with open(jsonfile, 'w') as f:
            json.dump({'token': token}, f)

    def decorator(fn):
        def wrapped(*args, **kwargs):
            if os.path.exists(jsonfile):
                token = get_token_from_file()
                if token:
                    return f'{token} (cached!!)'
            res = fn(*args, **kwargs)
            save_token_to_file(res)
            return res
          
        return wrapped
    return decorator


@cached_token('token-cache.json')
def get_token():
    # imaginary API call to get token
    import time; time.sleep(3)
    return '7c5d3ca5-0088-49a7-ae30-011931a44075'

print(get_token())