GUI can now send to say as concat string

src/testdata/http.go

@@ -11,7 +11,7 @@ func main() {
 	p := os.Getenv("PORT")
 	if err := http.ListenAndServe(":"+p, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		b, _ := io.ReadAll(r.Body)
-		log.Printf("> %s", b)
+		log.Printf("> %s (%+v) %s", r.URL, r.Header, b)
 		body := os.Getenv("BODY")
 		if body == "-" {
 			body = string(b)