This tested snippet should do it:
import re line = re.sub(r"</?\[\d+>", "", line)
Edit: Here’s a commented version explaining how it works:
line = re.sub(r""" (?x) # Use free-spacing mode. < # Match a literal '<' /? # Optionally match a "https://stackoverflow.com/" \[ # Match a literal '[' \d+ # Match one or more digits > # Match a literal '>' """, "", line)
Regexes are fun! But I would strongly recommend spending an hour or two studying the basics. For starters, you need to learn which characters are special: “metacharacters” which need to be escaped (i.e. with a backslash placed in front – and the rules are different inside and outside character classes.) There is an excellent online tutorial at: www.regular-expressions.info. The time you spend there will pay for itself many times over. Happy regexing!