A top-down recursive very simple parser

cactl.py

TREE = {
    'proxy': {
        '': proxy_list,
        'list': (proxy_list, ("username", False)),
        'info': (proxy_info, ("proxy_name", True)),
    },
    'auth': {
        '': auth_info,
        'info': (auth_info, ("token", False)),
        'login': (auth_login, ("username", False)),
        'logout': auth_logout,
    },
    'server': {
        '': server_url,
        'list': [server_url, {"listing": True}],
        'set': (server_url, ("url", True)),
        'add': (server_url, {"add": True}, ("url", True)),
        'remove': (server_url, {"remove": True}, ("url", True)),
    }
}

def parse_recursive(casino, tree, commands):
    if len(tree) == 0:
        print("No more arguments available")
        return None

    if len(commands) == 0:
        commands = ['']

    if commands[0] not in tree:
        expected = ', '.join([k for k in tree.keys() if k != ''])

        # help
        if commands[0] == '?' or commands[0] == 'help':
            print("Commands: {}".format(expected))
        else:
            print("Bad arguments, expected: {}".format(expected))

        return None

    node = tree[commands[0]]
    if isinstance(node, dict):
        return parse_recursive(casino, node, commands[1:])

    if hasattr(node, '__call__'):
        node = [node]

    if isinstance(node, (list, tuple)):
        function = node[0]
        accepted = node[1:]
        arguments = commands[1:]
        kargs = {}
        for element in accepted:
            # Extra arguments to send to the function
            if isinstance(element, dict):
                kargs.update(element)
                continue

            # Arguments that must be specified
            argname, required = element
            try:
                arg = arguments.pop(0)
                # help
                if arg == '?' or arg == 'help':
                    print("Argument: {}".format(argname))
                    return
            except (IndexError, AttributeError):
                if not required:
                    break
                else:
                    print("Missing arguments, expected: {}".format(argname))
                    return False

            kargs[argname] = arg

        function(casino, **kargs)

    return False