Async MQ ping-pong

Question

I have two sender-receivers. The first is written on Python and the second is on Golang. I used official sources of RabbitMQ documentation here and here.

Python code:

import pika
connection = pika.BlockingConnection(pika.ConnectionParameters('localhost'))
channel = connection.channel()
channel.queue_declare(queue='hello')
channel.basic_publish(exchange='',
 routing_key='hello',
 body='hello')
def callback(ch, method, properties, body):
 print(" [x] Received %r" % body)
 num = int(body[5:])
 num = num + 1
 channel.basic_publish(exchange='',
 routing_key='hello',
 body='hello'+str(num))
channel.basic_consume(callback,
 queue='hello',
 no_ack=True)
print(' [*] Waiting for messages. To exit press CTRL+C')
channel.start_consuming()
connection.close()

Golang receiver-sender:

package main
import (
 "log"
 "strconv"
 "fmt"
 "github.com/streadway/amqp"
)
func failOnError(err error, msg string) {
 if err != nil {
 log.Fatalf("%s: %s", msg, err)
 }
}
func main() {
 conn, err := amqp.Dial("amqp://guest:guest@localhost:5672/")
 failOnError(err, "Failed to connect to RabbitMQ")
 defer conn.Close()
 ch, err := conn.Channel()
 failOnError(err, "Failed to open a channel")
 defer ch.Close()
 q, err := ch.QueueDeclare(
 "hello", // name
 false, // durable
 false, // delete when unused
 false, // exclusive
 false, // no-wait
 nil, // arguments
 )
 failOnError(err, "Failed to declare a queue")
 msgs, err := ch.Consume(
 q.Name, // queue
 "", // consumer
 true, // auto-ack
 false, // exclusive
 false, // no-local
 false, // no-wait
 nil, // args
 )
 failOnError(err, "Failed to register a consumer")
 forever := make(chan bool)
 go func() {
 for d := range msgs {
 log.Printf("Received a message: %s", d.Body)
 s := string(d.Body)
 num, _ := strconv.ParseInt(s[5:], 0, 64)
 num++
 body := fmt.Sprintf("hello%d", num)
 err = ch.Publish(
 "", // exchange
 q.Name, // routing key
 false, // mandatory
 false, // immediate
 amqp.Publishing {
 ContentType: "text/plain",
 Body: []byte(body),
 })
 failOnError(err, "Failed to publish a message")
 }
 }()
 log.Printf(" [*] Waiting for messages. To exit press CTRL+C")
 <-forever
}

What can be improved here? May be I can use non-default exchange here? Are both pieces of my code working asynchronously?