Hook is a hook that writes logs of specified LogLevels to specified Writer
type Hook struct {
Writer io.Writer
LogLevels []log.Level
}
func (hook *Hook) Fire(entry *log.Entry) error
Fire will be called when some logging function is called with current hook It will format log entry to string and write it to appropriate writer
func (hook *Hook) Levels() []log.Level
Levels define on which log levels this hook would trigger