use assert[Not]In where appropriate
diff --git a/Lib/test/test_dict.py b/Lib/test/test_dict.py
index 075f9dc..6c0c65b 100644
--- a/Lib/test/test_dict.py
+++ b/Lib/test/test_dict.py
@@ -67,12 +67,13 @@
 
     def test_contains(self):
         d = {}
+        self.assertNotIn('a', d)
         self.assertTrue(not ('a' in d))
         self.assertTrue('a' not in d)
         d = {'a': 1, 'b': 2}
-        self.assertTrue('a' in d)
-        self.assertTrue('b' in d)
-        self.assertTrue('c' not in d)
+        self.assertIn('a', d)
+        self.assertIn('b', d)
+        self.assertNotIn('c', d)
 
         self.assertRaises(TypeError, d.__contains__)
 
@@ -430,8 +431,8 @@
         d = D({1: 2, 3: 4})
         self.assertEqual(d[1], 2)
         self.assertEqual(d[3], 4)
-        self.assertTrue(2 not in d)
-        self.assertTrue(2 not in d.keys())
+        self.assertNotIn(2, d)
+        self.assertNotIn(2, d.keys())
         self.assertEqual(d[2], 42)
         class E(dict):
             def __missing__(self, key):