'Given the `args` left unused by a `parse_global_options`,
return the invoked subcommand, the subcommand options, and the
subcommand arguments.'

def parse_subcommand(self, args):

    if (not args):
        args = ['help']
    cmdname = args.pop(0)
    subcommand = self._subcommand_for_name(cmdname)
    if (not subcommand):
        raise UserError(u"unknown    command    '{0}'".format(cmdname))
    (suboptions, subargs) = subcommand.parse_args(args)
    return (subcommand, suboptions, subargs)
