func (self *Logger) Println(msg string) {
	log.Println(msg)
	self.logger.Println(msg)
}
Println prints a message to console and Logger.file
package main
import (
	"log"
	"os"
)
type Logger struct {
	logger *log.Logger
	file   *os.File
}
func NewLogger(path string) *Logger {
	file, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
	if err != nil {
		log.Panic("can't open", path)
	}
	logger := log.New(file, "event-notify-log: ", log.Lshortfile|log.LstdFlags)
	return &Logger{logger, file}
}
func (self *Logger) Close() {
	err := self.file.Close()
	if err != nil {
		log.Println(err.Error())
	}
}