log

type InfoLogger interface {
	// Infof logs a formatted non-error message.
	Infof(format string, args ...interface{})
}

type Logger interface {
	// All Loggers implement InfoLogger.  Calling InfoLogger methods directly on
	// a Logger value is equivalent to calling them on a V(1) InfoLogger.  For
	// example, logger.Info() produces the same result as logger.V(1).Info.
	InfoLogger

	// Error logs an error message.  This is behaviorally akin to fmt.Println.
	Error(args ...interface{})

	// Errorf logs a formatted error message.
	Errorf(format string, args ...interface{})

	// V returns an InfoLogger value for a specific verbosity level. A higher
	// verbosity level means a log message is less important.
	V(level int) InfoLogger

	// NewWithPrefix returns a Logger which prefixes all messages.
	WithPrefix(prefix string) Logger
}