At least in neovim, `│vi:` is not recognized as a modeline because it
has no preceding whitespace. After fixing this, opening a file yields
an error because `net` is not an option. (`noet`, however, is.)
The final print does not print any content, only the byte-offset of the
end-block, which makes the A, B params unused. From gcc:
bd.c:77:17: warning: too many arguments for format [-Wformat-extra-args]
if (o) printf("%08x\n", o, A, B);