func Warningf(format string, args ...interface{}) {
	if logger != nil {
		logger.Warningf(format, args...)
	}
}
Warningf logs warning level messages.
package clog
import "log"
type Logger interface {
	Infof(format string, args ...interface{})
	Warningf(format string, args ...interface{})
	Errorf(format string, args ...interface{})
	Fatalf(format string, args ...interface{})
	V(int) bool
	SetV(level int)
}
var logger Logger = &stdlog{
	verbosity: 0,
}
func SetLogger(l Logger) { logger = l }
var verbosity int
func V(level int) bool {
	if logger == nil {
		return false
	}
	return logger.V(level)
}
func SetV(level int) {
	if logger != nil {
		logger.SetV(level)
	}
}
func Infof(format string, args ...interface{}) {
	if logger != nil {
		logger.Infof(format, args...)
	}
}