code: func NewDNSProviderConfig(config *Config) (*DNSProvider, error) {
  	if config == nil {
  		return nil, errors.New("linode: the configuration of the DNS provider is nil")
  	}
  
  	if len(config.APIKey) == 0 {
  		return nil, errors.New("linode: credentials missing")
  	}
  
  	if config.TTL < minTTL {
  		return nil, fmt.Errorf("linode: invalid TTL, TTL (%d) must be greater than %d", config.TTL, minTTL)
  	}
  
  	return &DNSProvider{
  		config: config,
  		client: dns.New(config.APIKey),
  	}, nil
  }
docs: // NewDNSProviderConfig return a DNSProvider instance configured for Linode.