logs

type Logger interface {
	io.Writer

	Info(msg string)
	Warn(msg string)
	Error(msg string)
	Fatal(msg string)

	Infof(format string, data ...interface{})
	Warnf(format string, data ...interface{})
	Errorf(format string, data ...interface{})
	Fatalf(format string, data ...interface{})
}