Unity Project

reference
https://cardgames.io/yahtzee/

Library/PackageCache/com.unity.timeline@1.2.15/Runtime/Events/Signals/CustomSignalEventDrawer.cs

@@ -0,0 +1,5 @@
+namespace UnityEngine.Timeline
+{
+    //used to tell Signal Handler inspector to use a special drawer for UnityEvent
+    class CustomSignalEventDrawer : PropertyAttribute {}
+}