A little clarity tweak to r4093

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/sqlalchemy/util.py b/lib/sqlalchemy/util.py
index bdcaf37f0..1f41c1179 100644
--- a/lib/sqlalchemy/util.py
+++ b/lib/sqlalchemy/util.py
@@ -192,7 +192,7 @@ def get_cls_kwargs(cls):
 
     for c in cls.__mro__:
         if '__init__' in c.__dict__:
-            stack = [c]
+            stack = Set([c])
             break
     else:
         return []
@@ -204,9 +204,9 @@ def get_cls_kwargs(cls):
         if not ctr or not isinstance(ctr, types.FunctionType):
             continue
         names, _, has_kw, _ = inspect.getargspec(ctr)
-        args |= Set(names)
+        args.update(names)
         if has_kw:
-            stack.extend(class_.__bases__)
+            stack.update(class_.__bases__)
     args.discard('self')
     return list(args)