logger.go
func (opt *Options) Debugf(format string, v ...interface{}) {
	if opt.Logger == nil {
		return
	}
	opt.Logger.Debugf(format, v...)
}
func (opt *Options) Debugf(format string, v ...interface{}) {
	if opt.Logger == nil {
		return
	}
	opt.Logger.Debugf(format, v...)
}
func ( opt * Options ) Debugf ( format string , v ... interface { } ) { if opt . Logger == nil { return } opt . Logger . Debugf ( format , v ... ) }
// Warningf logs a WARNING message to the logger specified in opts.
Warningf logs a WARNING message to the logger specified in opts .