Adding checkboxes in Python - display on page

I'm using Python to generate an HTML page; I have added a text file through an iframe and now I'm trying to add checkboxes to every line of the file. My webpage currently looks like this:

Title

username1

username2

username3

...

username[n]

I want to add the checkboxes dynamically inside the iframe (since my textfile keeps updating) and in the end to get something like this:

Title

[ ]username1

[ ]username2

[ ]username3

...

[ ]username[n]

I'be been going through SO the whole day and couldn't find anything that could help me. Any help is appreciated!