Get a result from the backend.

        Parameters:
          message(Message)
          block(bool): Whether or not to block until a result is set.
          timeout(int): The maximum amount of time, in ms, to wait for
            a result when block is True.  Defaults to 10 seconds.

        Raises:
          ResultMissing: When block is False and the result isn't set.
          ResultTimeout: When waiting for a result times out.

        Returns:
          object: The result.

def get_result(self, message, *, block: bool = False, timeout: int = None) -> Result:
        """Get a result from the backend.

        Parameters:
          message(Message)
          block(bool): Whether or not to block until a result is set.
          timeout(int): The maximum amount of time, in ms, to wait for
            a result when block is True.  Defaults to 10 seconds.

        Raises:
          ResultMissing: When block is False and the result isn't set.
          ResultTimeout: When waiting for a result times out.

        Returns:
          object: The result.
        """
        if timeout is None:
            timeout = DEFAULT_TIMEOUT

        end_time = time.monotonic() + timeout / 1000
        message_key = self.build_message_key(message)

        attempts = 0
        while True:
            result = self._get(message_key)
            if result is Missing and block:
                attempts, delay = compute_backoff(attempts, factor=BACKOFF_FACTOR)
                delay /= 1000
                if time.monotonic() + delay > end_time:
                    raise ResultTimeout(message)

                time.sleep(delay)
                continue

            elif result is Missing:
                raise ResultMissing(message)

            else:
                return result