use assert[Not]In where appropriate
diff --git a/Lib/test/test_multibytecodec.py b/Lib/test/test_multibytecodec.py
index f23e6e0..c74e329 100644
--- a/Lib/test/test_multibytecodec.py
+++ b/Lib/test/test_multibytecodec.py
@@ -222,7 +222,7 @@
         self.assertEqual(iso2022jp2.decode('iso2022-jp-2'), uni)
 
     def test_iso2022_jp_g0(self):
-        self.assertFalse('\x0e' in u'\N{SOFT HYPHEN}'.encode('iso-2022-jp-2'))
+        self.assertNotIn('\x0e', u'\N{SOFT HYPHEN}'.encode('iso-2022-jp-2'))
         for encoding in ('iso-2022-jp-2004', 'iso-2022-jp-3'):
             e = u'\u3406'.encode(encoding)
             self.assertFalse(filter(lambda x: x >= '\x80', e))