'Return access token as a JsonDict:
"access_token": "your-access-token",
"expires": 12345678, # represented using standard unix-epoch-time
"uid": 1234 # other fields'

def request_access_token(self, code, redirect_uri=None):

    r = self._mixin.request_access_token(code, redirect_uri)
    self._access_token = r.access_token
    return r
