附加到文件错误 - PYTHON

请耐心等待，因为我是 Python 的新手，并且正在通过创建简单的程序来学习。最近我开始制作我自己的程序来生成一个文件并允许用户选择内容并将它们存储在每个文件中。在这个例子中，我想要一个歌曲播放列表生成器。尽管这很困难，但我还是坚持了下来，直到遇到这个我无法修复的错误。这是打开一个文件。

这是代码

cont = "0"
log = 0
data = open("songs.txt", "r")
songs = data.readlines()
songs.sort()


while log < 20:
    cont = input("Do you want to make a playlist? [Yes or No]")
    while cont == "yes":
        print ("1. ", songs[0],"2. ", songs[1],"3. ", songs[2],"4. ", songs[3],"5. ", songs[4],"6. ", songs[5],"7. ", songs[6],"8. ", songs[7],"9. ", songs[8],"10. ", songs[9],"11. ", songs[10],"12. ", songs[11],"13. ", songs[12],"14. ", songs[13],"15. ", songs[14],"16. ", songs[15],"17. ", songs[16],"18. ", songs[17],"19. ", songs[18],"20. ", songs[19])
        new = "playlist" + str(log) + ".txt"
        print(new)
        log = log + 1
        cont = "no"
        choice = int(input("Please enter the first choice of song you would like in your playlist [Type the allocated number please]"))
        choice1 = choice - 1
        "playlist" + str(log) + ".txt".append(songs[choice1])

但是，我的代码应该允许用户从我的打印功能中选择歌曲，然后将它们添加到生成的播放列表中，然后对他们想要的任意数量的播放列表重复此操作。现在我的代码给了我一条错误消息。

File "playlists.py", line 18, in <module>
"playlist" + str(log) + ".txt".append(songs[choice1])
AttributeError: 'str' object has no attribute 'append'

这个错误说明了什么，以及我如何克服它。

提前致谢并期待！