Fix typos in code comment and documentation
diff --git a/Doc/library/argparse.rst b/Doc/library/argparse.rst
index c7b8cb7..2ea4b83 100644
--- a/Doc/library/argparse.rst
+++ b/Doc/library/argparse.rst
@@ -878,7 +878,7 @@
   See the nargs_ description for examples.
 
 With the ``'store_const'`` and ``'append_const'`` actions, the ``const``
-keyword argument must be given.  For other actions, is defaults to ``None``.
+keyword argument must be given.  For other actions, it defaults to ``None``.
 
 
 default