use assert[Not]In where appropriate
diff --git a/Lib/test/test_dbm.py b/Lib/test/test_dbm.py
index 43f8a5b..41b0b5c 100755
--- a/Lib/test/test_dbm.py
+++ b/Lib/test/test_dbm.py
@@ -21,9 +21,9 @@
             self.d[k] = v
         self.assertEqual(sorted(self.d.keys()), sorted(k for (k, v) in a))
         for k, v in a:
-            self.assertTrue(k in self.d)
+            self.assertIn(k, self.d)
             self.assertEqual(self.d[k], v)
-        self.assertTrue('xxx' not in self.d)
+        self.assertNotIn('xxx', self.d)
         self.assertRaises(KeyError, lambda: self.d['xxx'])
         self.d.close()