This fixes a regression from Python 2.  To get optional subparsers,
use the new parameter ``add_subparsers(required=False)``.

Patch by Anthony Sottile.

This adds support for parsing a command line where options and positionals are intermixed as is common in many unix commands. This is paul.j3's patch with a few tweaks.

Output of func(*args) stored in the next line:

    item_help = join([func(*args) for func, args in self.items])

_Section.items only used by HelpFormatter._add_item() and it looks
like it doesn't have any side effects.

Patch by Yogesh Chaudhari.

Patch by Matthias Bussonnier.

Patch by Jonathan Paugh, Steven Bethard, paul j3 and Daniel Eriksson.

implementation in issue #21408 they are redundant.

Before, if a default was set on the parent parser, any default for that
variable set via set_defaults on a subparser would be ignored.  Now
the subparser set_defaults is honored.

Patch by Jyrki Pullianinen.

Issue #21481:  Teach argparse equality tests to return NotImplemented when comparing to unknown types.

a help on environment with too small COLUMNS.  Based on patch by
Elazar Gershuni.

output to stdout, matching the 'python -v'

Reported by Wolfgang Maier

as reported by Serhiy Storchaka and Matthew Barnett.

Patch by Lucas Maystre.

on the action's default, reverting it back to previous behavior.  Conversion
is only done on string defaults.

Add a test for this and another test that ensures such type conversions are
only called once.

on the action's default, reverting it back to previous behavior.  Conversion
is only done on string defaults.

Add a test for this and another test that ensures such type conversions are
only called once.

  when action='append', type='str' and default=[].

  when action='append', type='str' and default=[].

This fixes a regression introduced by the fix for issue #13922.  Although args
is not documented as being allowed to be a tuple, previously this worked and
so naturally there are programs in the field that depend on it.

Patch by Zbyszek Jędrzejewski-Szmek.

This fixes a regression introduced by the fix for issue #13922.  Although args
is not documented as being allowed to be a tuple, previously this worked and
so naturally there are programs in the field that depend on it.

Patch by Zbyszek Jędrzejewski-Szmek.

Before, the type function was called twice in the case where the default
was specified and the argument was given as well.  This was especially
problematic for the FileType type, as a default file would always be
opened, even if a file argument was specified on the command line.

Patch by Arnaud Fontaine, with additional test by Mike Meyer.

Before, the type function was called twice in the case where the default
was specified and the argument was given as well.  This was especially
problematic for the FileType type, as a default file would always be
opened, even if a file argument was specified on the command line.

Patch by Arnaud Fontaine, with additional test by Mike Meyer.

Patch by Jeff Knupp.

Patch by Jeff Knupp.

Patch by Torsten Landschoff.

Patch by Torsten Landschoff.

Fix and initial test patch by Michele Orrù.