code: func (r *DNSResolvers) Set(value string) error {
  	entryPoints := strings.Split(value, ",")
  	if len(entryPoints) == 0 {
  		return fmt.Errorf("wrong DNSResolvers format: %s", value)
  	}
  	for _, entryPoint := range entryPoints {
  		*r = append(*r, entryPoint)
  	}
  	return nil
  }
docs: // Set is the method to set the flag value, part of the flag.Value interface.
  // Set's argument is a string to be parsed to set the flag.
  // It's a comma-separated list, so we split it.