♻️ Refactor: Use func in app.go

Remove if statement
Reduce Scope of Variable

app.go

@@ -683,27 +683,22 @@ func (app *App) GetRoutes(filterUseOption ...bool) []Route {
 //
 // This method will match all HTTP verbs: GET, POST, PUT, HEAD etc...
 func (app *App) Use(args ...interface{}) Router {
-	var prefix string
 	var prefixes []string
 	var handlers []Handler
 
-	for i := 0; i < len(args); i++ {
-		switch arg := args[i].(type) {
+	for _, arg := range args {
+		switch arg := arg.(type) {
 		case string:
-			prefix = arg
+			prefixes = append(prefixes, arg)
 		case []string:
-			prefixes = arg
+			prefixes = append(prefixes, arg...)
 		case Handler:
 			handlers = append(handlers, arg)
 		default:
 			panic(fmt.Sprintf("use: invalid handler %v\n", reflect.TypeOf(arg)))
 		}
 	}
 
-	if len(prefixes) == 0 {
-		prefixes = append(prefixes, prefix)
-	}
-
 	for _, prefix := range prefixes {
 		app.register(methodUse, prefix, nil, handlers...)
 	}