code: func NewDNSProvider() (*DNSProvider, error) {
  	values, err := env.Get("EXEC_PATH")
  	if err != nil {
  		return nil, fmt.Errorf("exec: %v", err)
  	}
  
  	config := NewDefaultConfig()
  	config.Program = values["EXEC_PATH"]
  	config.Mode = os.Getenv("EXEC_MODE")
  
  	return NewDNSProviderConfig(config)
  }
docs: // NewDNSProvider returns a new DNS provider which runs the program in the
  // environment variable EXEC_PATH for adding and removing the DNS record.