> The Unix m4 macro processor is probably the only widely used tool that uses the `quote' combination as part of its input syntax; however, even that could be m

> The Unix m4 macro processor is probably the only widely used tool that uses the `quote' combination as part of its input syntax; however, even that could be modified via changequote. I remember staring for a long time at the file when I first saw an m4 macro. My brain was telling, surely this has go to be a typo, but then everything worked as expected. Then I learned that's a proper way of quoting there.