【待解决】python写文件时报错：TypeError: a bytes-like object is required, not 'str'

for i in ans:
        lst = []
        lst.append(i[0].encode())
        lst.append(i[1].encode())
        print (type(lst[0]))
        writer.writerow(lst[0])

这个，现在依旧很迷啊！！！

PS C:\Users\Desktop\database> python total.py
<class 'bytes'>
Traceback (most recent call last):
  File "total.py", line 38, in <module>
    writer.writerow(lst[0])
TypeError: a bytes-like object is required, not 'str'

lst[0]就是Bytes类型啊，咋还报这个错？路过的大佬帮帮忙啊！