improve docs

cmd/any2anexoj-cli/main.go

@@ -25,7 +25,7 @@ var (
 	format   = pflag.StringP("format", "f", "table", "Output format: table or csv")
 	ofAPIKey = pflag.String("open-figi-api-key", "", "An OpenFIGI API key for faster report generation (better rate api rate limits)")
 	// TODO: improve documentation on selectors
-	selectors = pflag.StringSlice("selectors", nil, "Only process entries that conform to all the selectors:")
+	selectors = pflag.StringSlice("selectors", nil, "Only process entries that conform to all the selectors: code, assetCountry")
 )
 
 func main() {
@@ -51,13 +51,11 @@ func run(ctx context.Context) error {
 	slog.SetDefault(slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: logLevel})))
 
 	if platform == nil || len(*platform) == 0 {
-		slog.Error("--platform flag is required")
-		os.Exit(1)
+		return fmt.Errorf("--platform flag is required")
 	}
 
 	if lang == nil || len(*lang) == 0 {
-		slog.Error("--language flag is required")
-		os.Exit(1)
+		return fmt.Errorf("--language flag is required")
 	}
 
 	reader, err := getReader(*platform, *ofAPIKey)

internal/selectors.go

@@ -16,12 +16,15 @@ func And(a, b Selector) Selector {
 	}
 }
 
+// OnlyNature will only select records with the given Nature n (G01, G20, etc...).
 func OnlyNature(n Nature) Selector {
 	return func(r Record) bool {
 		return r.Nature() == n
 	}
 }
 
+// OnlyAssetCountry will only select records with the given ISO code c (620 for Portugal, 196 for
+// Cyprus, etc...).
 func OnlyAssetCountry(c int64) Selector {
 	return func(r Record) bool {
 		return r.AssetCountry() == c