I've found if you can break up a regex into verbose form, and debug it on a app or site like regex101.com, you can figure out just about any expression. Then ad

I've found if you can break up a regex into verbose form, and debug it on a app or site like regex101.com, you can figure out just about any expression. Then add comments with that understanding. That may not extend to the email address-parsing monstrosity that was given, but I think it would still help considerably.