Fix a few grammar problems in the documentation and comments
diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
index ecc5507..5efdb67 100644
--- a/Lib/test/test_argparse.py
+++ b/Lib/test/test_argparse.py
@@ -3019,7 +3019,7 @@
     '''Test extremely small number of columns.
 
     TestCase prevents "COLUMNS" from being too small in the tests themselves,
-    but we don't want any exceptions thrown in such case. Only ugly representation.
+    but we don't want any exceptions thrown in such cases. Only ugly representation.
     '''
     def setUp(self):
         env = support.EnvironmentVarGuard()