If it was something I had not seen before (which is already extremely unlikely given that I've spent a significant amount of time reading the official spec of t

If it was something I had not seen before (which is already extremely unlikely given that I've spent a significant amount of time reading the official spec of the language to write a parser...) I'd still have given them the benefit of the doubt and maybe asked to clarify what they were doing. More than correcting people, I love learning new obscure things.