regex = None method = None while opt != 0: print(main_menu) opt = input('> ') if opt == '1': print(type_regex_msg) regex = input('> ') try: reader = Reader(regex) tokens = reader.CreateTokens() parser = Parser(tokens) tree = parser.Parse() direct_reader = DirectReader(regex) direct_tokens = direct_reader.CreateTokens() direct_parser = Parser(direct_tokens) direct_tree = direct_parser.Parse() print('\n\tExpression accepted!') print('\tParsed tree:', tree) except AttributeError as e: print(f'\n\tERR: Invalid expression (missing parenthesis)') except Exception as e: print(f'\n\tERR: {e}') if opt == '2':