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: formatter.go
    path of file: ./repos/docker-ce/components/engine/vendor/github.com/RackSec/srslog
    
    the code of the file until where you have to start completion: package srslog

import (
	"fmt"
	"os"
	"time"
)

const appNameMaxLength = 48 // limit to 48 chars as per RFC5424

// Formatter is a type of function that takes the consituent parts of a
// syslog mes
    
func RFC5424Formatter(p Priority, hostname, tag, content string) string {
	timestamp := time.Now().Format(time.RFC3339)
	pid := os.Getpid()
	appName := truncateStartStr(os.Args[0], appNameMaxLength)
	msg := fmt.Sprintf("<%d>%d %s %s %s %d %s - %s",
		p, 1, timestamp, hostname, appName, pid, tag, content)
	return msg
}