code: func (ch *Channel) Close() error {
  	defer ch.connection.closeChannel(ch, nil)
  	return ch.call(
  		&channelClose{ReplyCode: replySuccess},
  		&channelCloseOk{},
  	)
  }
docs: /*
  Close initiate a clean channel closure by sending a close message with the error
  code set to '200'.
  
  It is safe to call this method multiple times.
  
  */