Unity Project

reference
https://cardgames.io/yahtzee/

Library/PackageCache/com.unity.timeline@1.2.15/Runtime/AssetUpgrade/TimelineUpgrade.cs

@@ -0,0 +1,21 @@
+namespace UnityEngine.Timeline
+{
+    partial class TimelineAsset
+    {
+        enum Versions
+        {
+            Initial = 0
+        }
+        const int k_LatestVersion = (int)Versions.Initial;
+        [SerializeField, HideInInspector] int m_Version;
+
+        //fields that are used for upgrading should be put here, ideally as read-only
+
+        void UpgradeToLatestVersion()
+        {}
+
+        //upgrade code should go into this class
+        static class TimelineAssetUpgrade
+        {}
+    }
+}