code: func (c *channel) responseMessageReceived() error {
  	if c.direction == channelInbound {
  		return errors.New("ssh: channel response message received on inbound channel")
  	}
  	if c.decided {
  		return errors.New("ssh: duplicate response received for channel")
  	}
  	c.decided = true
  	return nil
  }
docs: // responseMessageReceived is called when a success or failure message is
  // received on a channel to check that such a message is reasonable for the
  // given channel.