How to use the webtech.utils.FileNotFoundException function in webtech

def get_random_user_agent():
    """
    Get a random user agent from a file
    """
    ua_file = os.path.join(os.path.realpath(os.path.dirname(__file__)), "ua.txt")
    try:
        with open(ua_file) as f:
            agents = f.readlines()
            return random.choice(agents).strip()
    except FileNotFoundException as e:
        print(e)
        print('Please: Reinstall webtech correctly or provide a valid User-Agent list')
        exit(-1)

if options.get('database_file'):
            try:
                with open(options.get('database_file')) as f:
                    self.db = database.merge_databases(self.db, json.load(f))
            except (FileNotFoundException, ValueError) as e:
                print(e)
                exit(-1)

        self.urls = options.get('urls') or []

        if options.get('urls_file'):
            try:
                with open(options.get('urls_file')) as f:
                    self.urls = [line.rstrip() for line in f]
            except FileNotFoundException as e:
                print(e)
                exit(-1)

        if options.get('user_agent'):
            self.USER_AGENT = options.get('user_agent')
        elif options.get('random_user_agent'):
            self.USER_AGENT = get_random_user_agent()

        if options.get('grep'):
            # Greppable output
            self.output_format = Format['grep']
        elif options.get('json'):
            # JSON output
            self.output_format = Format['json']

        try: