- @# sed-fu: remove the "@" from "//@", and remove trailing "/*@*/".
- @sed 's|^\(\s*//\)@|\1|;s|\s*/\*@\*/$$||' $< > $@
+ @# sed-fu: remove the "@" from "//@", and remove trailing "/*@*/", replace lines ending in "/*@@*/" by "unimplemented!()".
+ @# Also coalesce multiple adjacent such lines to one.
+ @sed 's|^\(\s*//\)@|\1|;s|\s*/\*@\*/$$||;s|\(\s*\)\S.*/\*@@\*/|\1unimplemented!()|' $< | sed -f dup-unimpl.sed > $@