responsive way to write in a specific line in python?

Question

I know that reading a specific line is possible with:

i = 0
while True:
    with open("file.txt") as f:
        f = f.readlines()[i]
    i += 1

So I wondered if there is any responsive way to write to a specific line, but this doesn't seem to be working:

i = 0
while True:
    with open("file.txt", 'w') as f:
        f = f.writelines(str(episode))[i]
    i += 1

But this alone does work:

with open("file.txt", 'w') as f:
    f = f.writelines(str(episode))