Appending to a text string

[syno7878]

Hi

I tried your code and I got the following error message. I'm using Python 2.7:

invalid syntax: test.py, line 4, pos 39 in file C:\python-scripts\test.py
f_out.write(f'{line} {index}\n')

The print operation is doing this correctly:

f = open("password.txt", "rt")
s = f.read()
f = open("password2.txt", "wt")

for count in range(1900,2021):
    s+str(count)
    print({s},{count})

But how do I write this operation to a file. I only have one line in the file which is password.

Thanks