async def _auth_handler_post_get_auth(self):
        '''
        If the user supplied auth does rely on a response
        (is a PostResponseAuth object) then we call the auth's __call__
        returning a dict to update the request's headers with, as long
        as there is an appropriate 401'd response object to calculate auth
        details from.
        '''
        # pylint: disable=not-callable
        if isinstance(self.auth, PostResponseAuth):
            if self.history_objects:
                authable_resp = self.history_objects[-1]
                if authable_resp.status_code == 401:
                    if not self.auth.auth_attempted:
                        self.auth.auth_attempted = True
                        return await self.auth(authable_resp, self)
        return {}