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