I have this nested dictionary that I get from an API.

```
response_body = \
{  
    u'access_token':u'SIF_HMACSHA256lxWT0K',
    u'expires_in':86000,
    u'name':u'Gandalf Grey',
    u'preferred_username':u'gandalf',
    u'ref_id':u'ab1d4237-edd7-4edd-934f-3486eac5c262',
    u'refresh_token':u'eyJhbGciOiJIUzI1N',
    u'roles':u'Instructor',
    u'sub':{  
        u'cn':u'Gandalf Grey',
        u'dc':u'7477',
        u'uid':u'gandalf',
        u'uniqueIdentifier':u'ab1d4237-edd7-4edd-934f-3486eac5c262'
    }
}

```

I used the following to convert it into a Python object:

```
class sample_token:
    def __init__(self, **response):
        self.__dict__.update(response)

```

and used it like this:

```
s = sample_token(**response_body)

```

After this, I can access the values using `s.access_token`, `s.name` etc. But the value of `c.sub` is also a dictionary. How can I get the values of the nested dictionary using this technique? i.e. `s.sub.cn` returns `Gandalf Grey`.