That explains it, thanks. Amusingly the wikipedia "longest common subsequence" page emphasises that this is different to and commonly confused with the "longest

That explains it, thanks. Amusingly the wikipedia "longest common subsequence" page emphasises that this is different to and commonly confused with the "longest common substring". Illustrating this confusion neatly, the OP's repository implements subsequence, but is not only called substring but documented by a wikipedia link to substring!