You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: client.go
    path of file: ./repos/kubeedge/vendor/github.com/eclipse/paho.mqtt.golang
    
    the code of the file until where you have to start completion: /*
 * Copyright (c) 2013 IBM Corp.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Seth Hoenig
 *    Allan Stockdill-Mander
 *    Mi
    
func (c *client) Publish(topic string, qos byte, retained bool, payload interface{}) Token {
	token := newToken(packets.Publish).(*PublishToken)
	DEBUG.Println(CLI, "enter Publish")
	switch {
	case !c.IsConnected():
		token.setError(ErrNotConnected)
		return token
	case c.connectionStatus() == reconnecting && qos == 0:
		token.flowComplete()
		return token
	}
	pub := packets.NewControlPacket(packets.Publish).(*packets.PublishPacket)
	pub.Qos = qos
	pub.TopicName = topic
	pub.Retain = retained
	switch payload.(type) {
	case string:
		pub.Payload = []byte(payload.(string))
	case []byte:
		pub.Payload = payload.([]byte)
	default:
		token.setError(fmt.Errorf("Unknown payload type"))
		return token
	}

	if pub.Qos != 0 && pub.MessageID == 0 {
		pub.MessageID = c.getID(token)
		token.messageID = pub.MessageID
	}
	persistOutbound(c.persist, pub)
	if c.connectionStatus() == reconnecting {
		DEBUG.Println(CLI, "storing publish message (reconnecting), topic:", topic)
	} else {
		DEBUG.Println(CLI, "sending publish message, topic:", topic)
		c.obound <- &PacketAndToken{p: pub, t: token}
	}
	return token
}