logger.go
func (dl *DefaultLogger) Critical(message string, params ...interface{}) {
	dl.logger.Criticalf(fmt.Sprintf("%s %s", caller(), message), params...)
}
func (dl *DefaultLogger) Critical(message string, params ...interface{}) {
	dl.logger.Criticalf(fmt.Sprintf("%s %s", caller(), message), params...)
}
// Critical formats a given message according to given params to log with level Critical.