diff --git a/Lib/idlelib/StackViewer.py b/Lib/idlelib/StackViewer.py
index 36507eea684..e62e6f5586d 100644
--- a/Lib/idlelib/StackViewer.py
+++ b/Lib/idlelib/StackViewer.py
@@ -120,6 +120,9 @@ class VariablesTreeItem(ObjectTreeItem):
             sublist.append(item)
         return sublist
 
+    def keys(self):  # unused, left for possible 3rd parcy use
+        return list(self.object.keys())
+
 def _stack_viewer(parent):
     root = tk.Tk()
     root.title("Test StackViewer")