use assert[Not]IsInstance where appropriate
diff --git a/Lib/test/test_future5.py b/Lib/test/test_future5.py
index 1e1a930..4984070 100644
--- a/Lib/test/test_future5.py
+++ b/Lib/test/test_future5.py
@@ -9,7 +9,7 @@
 class TestMultipleFeatures(unittest.TestCase):
 
     def test_unicode_literals(self):
-        self.assertTrue(isinstance("", unicode))
+        self.assertIsInstance("", unicode)
 
     def test_print_function(self):
         with test_support.captured_output("stderr") as s: