Merge with 3.2.

diff --cc Doc/library/argparse.rst
index 25f8fa18985953eeeb34e7c2b51c64d2d2dc8b98,61e1786b017a8993be5aa1a87e9006668fe11de9..a2bceae15c3772d6d582e7384158c8cfafa88a97
--- 1/Doc/library/argparse.rst
--- 2/Doc/library/argparse.rst
+++ b/Doc/library/argparse.rst
@@@ -361,10 -362,16 +362,16 @@@ formatter_clas
  ^^^^^^^^^^^^^^^
  
  :class:`ArgumentParser` objects allow the help formatting to be customized by
- specifying an alternate formatting class.
 -specifying an alternate formatting class.  Currently, there are three such
++specifying an alternate formatting class.  Currently, there are four such
+ classes:
+ 
+ .. class:: RawDescriptionHelpFormatter
+            RawTextHelpFormatter
+            ArgumentDefaultsHelpFormatter
++           MetavarTypeHelpFormatter
  
 -The first two allow more control over how textual descriptions are displayed,
 -while the last automatically adds information about argument default values.
 -
 +:class:`RawDescriptionHelpFormatter` and :class:`RawTextHelpFormatter` give
 +more control over how textual descriptions are displayed.
  By default, :class:`ArgumentParser` objects line-wrap the description_ and
  epilog_ texts in command-line help messages::