add cron setting

pkg/set/set.go

@@ -22,7 +22,7 @@ func (s Set) Size() int {
 func (s Set) Keys() []interface{} {
 	keys := make([]interface{}, 0)
 
-	for k, _ := range s {
+	for k := range s {
 		keys = append(keys, k)
 	}