log

type Configuration struct {
	// Level of logging (panic, fatal, error, warn, info, default: debug)
	Level string
	// Output (default: os.Stdout)
	Output io.Writer
}

type Fields map[string]interface{}

type Logger interface {
	Debug(args ...interface{})
	DebugWithFields(fields map[string]interface{}, args ...interface{})

	Info(args ...interface{})
	InfoWithFields(fields map[string]interface{}, args ...interface{})

	Warn(args ...interface{})
	WarnWithFields(fields map[string]interface{}, args ...interface{})

	Error(args ...interface{})
	ErrorWithFields(fields map[string]interface{}, args ...interface{})

	Fatal(args ...interface{})
	FatalWithFields(fields map[string]interface{}, args ...interface{})

	Panic(args ...interface{})
	PanicWithFields(fields map[string]interface{}, args ...interface{})
}