I find my newly added header file not following the style guide Header guards should use #pragma once.

Looks like this is not unique

$ for f in `find include/ source/ test/ -name "*.h"`; do grep "pragma once" $f >/dev/null|| echo $f; done | wc -l
81

I will blindly add the pragma directive to make the future include no-brain.

Do we need a rule formatter to check/fix after the above change?