Print help

def cmd_help(self, argv, help):
        """Print help"""
        parser = argparse.ArgumentParser(
            prog="%s help" % self.progname,
            description=help,
        )
        parser.add_argument('-z', '--zsh',
                            action='store_true',
                            help="Print info for zsh autocompletion")
        parser.add_argument("command", nargs='?',
                            metavar="command",
                            help="Name of the command you want help for.",
                            choices=self.subparsers.keys())
        args = parser.parse_args(argv)
        if args.zsh:
            if args.command is None:
                for cmd in self.subparsers.keys():
                    print(cmd)
            else:  # pragma: no cover
                if hasattr(self.cmds[args.command], 'get_completion'):
                    for item in self.cmds[args.command].get_completion():
                        print(item)
                elif args.command in ('do', 'ssh'):
                    for instance in self.get_instances(command='init_ssh_key'):
                        print(instance)
                elif args.command == 'debug':
                    for instance in sorted(self.instances):
                        print(instance)
                elif args.command == 'list':
                    for subcmd in sorted(self.list_cmds):
                        print(subcmd)
                elif args.command != 'help':
                    for instance in sorted(self.get_instances(command=args.command)):
                        print(instance)
        else:
            if args.command is None:
                parser.print_help()
            else:
                cmd = self.cmds[args.command]
                cmd(['-h'], cmd.__doc__)