Fix few typos.
diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py
index 7d1649c..2ba3ea5 100644
--- a/Lib/test/test_ast.py
+++ b/Lib/test/test_ast.py
@@ -290,7 +290,7 @@
         self.assertEqual(x.body, body)
 
     def test_nodeclasses(self):
-        # Zero arguments constructor explicitely allowed
+        # Zero arguments constructor explicitly allowed
         x = ast.BinOp()
         self.assertEqual(x._fields, ('left', 'op', 'right'))