func (pl *PrefixLogger) Warningf(format string, args ...interface{}) {
	if pl != nil {
		format = pl.prefix + format
		pl.logger.WarningDepth(1, fmt.Sprintf(format, args...))
		return
	}
	WarningDepth(1, fmt.Sprintf(format, args...))
}
Warningf does warning logging.
package grpclog
import (
	"fmt"
)
type PrefixLogger struct {
	logger DepthLoggerV2
	prefix string
}
func (pl *PrefixLogger) Infof(format string, args ...interface{}) {
	if pl != nil {
		format = pl.prefix + format
		pl.logger.InfoDepth(1, fmt.Sprintf(format, args...))
		return
	}
	InfoDepth(1, fmt.Sprintf(format, args...))
}