use assert[Not]IsInstance where appropriate
diff --git a/Lib/test/test_dict.py b/Lib/test/test_dict.py
index 6c0c65b..b458ffd 100644
--- a/Lib/test/test_dict.py
+++ b/Lib/test/test_dict.py
@@ -225,7 +225,7 @@
                 return UserDict.UserDict()
         ud = mydict.fromkeys('ab')
         self.assertEqual(ud, {'a':None, 'b':None})
-        self.assertTrue(isinstance(ud, UserDict.UserDict))
+        self.assertIsInstance(ud, UserDict.UserDict)
         self.assertRaises(TypeError, dict.fromkeys)
 
         class Exc(Exception): pass