import argparse

class MyFormatter(argparse.HelpFormatter):
    """
    Corrected _max_action_length for the indenting of subactions
    """
    def add_argument(self, action):
        if action.help is not argparse.SUPPRESS:

            # find all invocations
            get_invocation = self._format_action_invocation
            invocations = [get_invocation(action)]
            current_indent = self._current_indent
            for subaction in self._iter_indented_subactions(action):
                # compensate for the indent that will be added
                indent_chg = self._current_indent - current_indent
                added_indent = 'x'*indent_chg
                invocations.append(added_indent+get_invocation(subaction))
            # print('inv', invocations)

            # update the maximum item length
            invocation_length = max([len(s) for s in invocations])
            action_length = invocation_length + self._current_indent
            self._action_max_length = max(self._action_max_length,
                                          action_length)

            # add the item to the list
            self._add_item(self._format_action, [action])

# call class with alternate parameters
formatter_class=lambda prog: MyFormatter(prog, max_help_position=40,width=100)

parser = argparse.ArgumentParser(formatter_class=formatter_class)

parser.add_argument('-l','--long', help='help after long option strings')

subparsers = parser.add_subparsers(title="Commands", metavar="<command>")

cmd_parser = subparsers.add_parser('long_long_cmd',
                                   help='longish command',
                                   formatter_class=formatter_class,
                                   aliases=['long', 'long_cmd'])
                                   # newer arpgarse take aliases
sht_parser = subparsers.add_parser('short', help = 'short cmd')

args = parser.parse_args(['-h'])

"""
which produces:

1355:~/mypy$ python3.5 issue25297.py
usage: issue25297.py [-h] [-l LONG] <command> ...

optional arguments:
  -h, --help                        show this help message and exit
  -l LONG, --long LONG              help after long option strings

Commands:
  <command>
    long_long_cmd (long, long_cmd)  longish command
    short                           short cmd


"""