Add subparser aliases for argparse. Resolves issue 9324. Approved by Georg for beta2 on the tracker.

Doc/library/argparse.rst

@@ -1428,6 +1428,16 @@ Sub-commands
 
        {foo,bar}   additional help
 
+   Furthermore, ``add_parser`` supports an additional ``aliases`` argument,
+   which allows multiple strings to refer to the same subparser. This example,
+   like ``svn``, aliases ``co`` as a shorthand for ``checkout``::
+
+     >>> parser = argparse.ArgumentParser()
+     >>> subparsers = parser.add_subparsers()
+     >>> checkout = subparsers.add_parser('checkout', aliases=['co'])
+     >>> checkout.add_argument('foo')
+     >>> parser.parse_args(['co', 'bar'])
+     Namespace(foo='bar')
 
    One particularly effective way of handling sub-commands is to combine the use
    of the :meth:`add_subparsers` method with calls to :meth:`set_defaults` so
@@ -1466,7 +1476,7 @@ Sub-commands
      >>> args.func(args)
      ((XYZYX))
 
-   This way, you can let :meth:`parse_args` does the job of calling the
+   This way, you can let :meth:`parse_args` do the job of calling the
    appropriate function after argument parsing is complete.  Associating
    functions with actions like this is typically the easiest way to handle the
    different actions for each of your subparsers.  However, if it is necessary