code: func NewDefaultConfig() *Config {
  	return &Config{
  		TTL:                env.GetOrDefaultInt("VULTR_TTL", dns01.DefaultTTL),
  		PropagationTimeout: env.GetOrDefaultSecond("VULTR_PROPAGATION_TIMEOUT", dns01.DefaultPropagationTimeout),
  		PollingInterval:    env.GetOrDefaultSecond("VULTR_POLLING_INTERVAL", dns01.DefaultPollingInterval),
  		HTTPClient: &http.Client{
  			Timeout: env.GetOrDefaultSecond("VULTR_HTTP_TIMEOUT", 0),
  			// from Vultr Client
  			Transport: &http.Transport{
  				TLSNextProto: make(map[string]func(string, *tls.Conn) http.RoundTripper),
  			},
  		},
  	}
  }
docs: // NewDefaultConfig returns a default configuration for the DNSProvider