You provide list context to read_file, only to then glue all the lines back together anyway.

Oops. That join is a left over bit of an earlier, more complex, attempt. Because Perl doesn't care about double newlines, and I didn't test with multi-line strings, and haven't even looked at line numbers, I never noticed that anything was wrong.

You are of course right that simple concatenation is better here. I'll update the node right away.