Store some values that aren't directly provided by a Web API
        response.

def _add_custom_values_to_token_info(self, token_info):
        '''
        Store some values that aren't directly provided by a Web API
        response.
        '''
        token_info['expires_at'] = int(time.time()) + token_info['expires_in']
        token_info['scope'] = self.scope
        return token_info