use assert[Not]In where appropriate
diff --git a/Lib/test/seq_tests.py b/Lib/test/seq_tests.py
index 14303aa..cf3ae8e 100644
--- a/Lib/test/seq_tests.py
+++ b/Lib/test/seq_tests.py
@@ -201,9 +201,9 @@
     def test_contains(self):
         u = self.type2test([0, 1, 2])
         for i in u:
-            self.assert_(i in u)
+            self.assertIn(i, u)
         for i in min(u)-1, max(u)+1:
-            self.assert_(i not in u)
+            self.assertNotIn(i, u)
 
         self.assertRaises(TypeError, u.__contains__)
 
@@ -215,8 +215,8 @@
             def __eq__(self, other):
                 return True
             __hash__ = None # Can't meet hash invariant requirements
-        self.assert_(AllEq() not in self.type2test([]))
-        self.assert_(AllEq() in self.type2test([1]))
+        self.assertNotIn(AllEq(), self.type2test([]))
+        self.assertIn(AllEq(), self.type2test([1]))
 
     def test_contains_order(self):
         # Sequences must test in-order.  If a rich comparison has side
@@ -229,7 +229,7 @@
                 raise DoNotTestEq
 
         checkfirst = self.type2test([1, StopCompares()])
-        self.assert_(1 in checkfirst)
+        self.assertIn(1, checkfirst)
         checklast = self.type2test([StopCompares(), 1])
         self.assertRaises(DoNotTestEq, checklast.__contains__, 1)