How to make a program that replaces newlines in python file with a string

I am trying to display my python file in html and therefore I would like to replace every time the file jumps to a newline with < br> but the program I've written is not working.

I've looked on here and tried changing the code around a bit I have gotten different results but not the ones I need.

with open(path, "r+") as file:
    contents = file.read()
contents.replace("\n", "<br>")
print(contents)
file.close()

I want to have the file display < br> every time I have a new line but instead the code dosen't change anything to the file.

Try this:

import re

with open(path, "r") as f:
    contents = f.read()
    contents = re.sub("\n", "<br>", contents)
    print(contents)