code simplification

models/data.go

@@ -1,7 +1,7 @@
 package models
 
 import (
-	"fmt"
+	"strings"
 	"time"
 )
 
@@ -49,15 +49,7 @@ func (s SpecialCake) Detail() string {
 	if len(parts) == 0 {
 		return ""
 	}
-	return fmt.Sprintf("(%s)", joinParts(parts))
-}
-
-func joinParts(parts []string) string {
-	out := parts[0]
-	for i := 1; i < len(parts); i++ {
-		out += ", " + parts[i]
-	}
-	return out
+	return "(" + strings.Join(parts, ", ") + ")"
 }
 
 type Order struct {