阅读下列代码,逐行简述代码的作用或意义. b = 5 try: assert b >= 6, "a超出范围" except AssertionError as error: print(error) else: try: with open('file.log') as file: read_data = file.read() except FileNotFoundError as fnf_error: print(fnf_error) finally: print('这句话,无论异常是否发生都会执行.')