code: func NewDNSProvider() (*DNSProvider, error) {
  	values, err := env.GetWithFallback(
  		[]string{"CLOUDFLARE_EMAIL", "CF_API_EMAIL"},
  		[]string{"CLOUDFLARE_API_KEY", "CF_API_KEY"})
  	if err != nil {
  		return nil, fmt.Errorf("cloudflare: %v", err)
  	}
  
  	config := NewDefaultConfig()
  	config.AuthEmail = values["CLOUDFLARE_EMAIL"]
  	config.AuthKey = values["CLOUDFLARE_API_KEY"]
  
  	return NewDNSProviderConfig(config)
  }
docs: // NewDNSProvider returns a DNSProvider instance configured for Cloudflare.
  // Credentials must be passed in the environment variables:
  // CLOUDFLARE_EMAIL and CLOUDFLARE_API_KEY.