The chosen implementation makes sep=XXX valid as long as XXX adheres to the current restrictions for sep_char. This implies IIRC a maximum length of 16 bytes, UTF-8 allowed.

I have entered the long procedure for testing. Just keep a keen eye on your favorite CPAN mirror.

For additional pleasure, the new version will have a say method too, so you don't need two object side by side: you can now use the same object for both reading and writing.