Not everything has to be OO. That's why I enjoy Perl and C++; their designers appreciated that OO is not necessarily the best solution to all problems.

Yes! The more I reflect on this, the more I realise the folly of the question.
However, asking a question that perhaps didn't need asking has elicited lots of insightful information and opinions. A useful bi-product 😊

Rather than starting from scratch, you might like to model your new module on your favourite from these three

I wasn't so much thinking of starting entirely from scratch as the methodology of calculating the Grade Score will be the same. I was thinking of just changing the regexp and copying the rest of the module. But I shall reach out to the other authors.