Fix signature for modified_json example (#7709)

diff --git a/lib/sqlalchemy/ext/mutable.py b/lib/sqlalchemy/ext/mutable.py
index d75cf667bd7eaa303ea4fe1abf40f26d55066f9d..7f3aad8b0ca58e3261c686b49c1267e7b7349e73 100644 (file)
--- a/lib/sqlalchemy/ext/mutable.py
+++ b/lib/sqlalchemy/ext/mutable.py
@@ -219,7 +219,7 @@ from within the mutable extension::
         data = Column(MutableDict.as_mutable(JSONEncodedDict))
 
     @event.listens_for(MyDataClass.data, "modified")
-    def modified_json(instance):
+    def modified_json(instance, initiator):
         print("json value modified:", instance.data)
 
 .. _mutable_composites: