Thanks you, that does make sense. Can I suggest adding that explanation to your article so it's clear that the example actually does do more than simply switch

Thanks you, that does make sense. Can I suggest adding that explanation to your article so it's clear that the example actually does do more than simply switching on a singular requested format? (I'm actually curious in practice how often the "Accept" header is really used to specify the format, and how often the format is simply coming from the extension on the requested path. I've only ever encountered the latter case, which I why I was thinking of the format as a single-valued variable you can switch on.)