logging.go
func (logger *Logger) Warningf(format string, a ...interface{}) {
	logger.log(WARNING, format, a...)
}
func (logger *Logger) Warningf(format string, a ...interface{}) {
	logger.log(WARNING, format, a...)
}
func ( logger * Logger ) Warningf ( format string , a ... interface { } ) { logger . log ( WARNING , format , a ... ) }
// Warningf logs provided message with formatting in WARNING level.
Warningf logs provided message with formatting in WARNING level .