add type for _is_closed

diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py
index 7c98a9020dc8d0a106f27e7da18d1f31b80bbe0a..aab04d7916db95e36a4f8a26f70f22fde959276e 100644 (file)
--- a/lib/sqlalchemy/orm/session.py
+++ b/lib/sqlalchemy/orm/session.py
@@ -1678,7 +1678,7 @@ class Session(_SessionClassMethods, EventTarget):
         self.expire_on_commit = expire_on_commit
         self.enable_baked_queries = enable_baked_queries
         self.close_final = close_final
-        self._is_closed = False
+        self._is_closed: bool = False
         if (
             join_transaction_mode
             and join_transaction_mode