How to detect with python if the string contains html code?

Question

How to detect either the string contains an html (can be html4, html5, just partials of html within text)? I do not need a version of HTML, but rather if the string is just

Answer 1

Expanding on the previous post I would do something like this for something quick and simple:

import sys, os

if os.path.exists("file.html"):
    checkfile=open("file.html", mode="r", encoding="utf-8")
    ishtml = False
    for line in checkfile:
        line=line.strip()
        if line == ""
            ishtml = True
    if ishtml:
        print("This is an html file")
    else:
        print("This is not an html file")