code: func NewDNSProviderConfig(config *Config) (*DNSProvider, error) {
  	if config == nil {
  		return nil, errors.New("dnspod: the configuration of the DNS provider is nil")
  	}
  
  	if config.LoginToken == "" {
  		return nil, fmt.Errorf("dnspod: credentials missing")
  	}
  
  	params := dnspod.CommonParams{LoginToken: config.LoginToken, Format: "json"}
  
  	client := dnspod.NewClient(params)
  	client.HttpClient = config.HTTPClient
  
  	return &DNSProvider{client: client, config: config}, nil
  }
docs: // NewDNSProviderConfig return a DNSProvider instance configured for dnspod.