diff --git a/list-type.go b/list-type.go
index f97990e..5b9eba7 100644
--- a/list-type.go
+++ b/list-type.go
@@ -147,3 +147,13 @@ func deepSame(a, b any, deepCmp deepFuncTemplate) (eq bool, err error) {
 
 	return
 }
+
+func (list *ListType) setItem(index int64, value any) (err error) {
+	if index >= 0 && index < int64(len(*list)) {
+		(*list)[index] = value
+	} else {
+		err = fmt.Errorf("index %d out of bounds (0, %d)", index, len(*list)-1)
+	}
+	return
+}
+