Plan 9 from Bell Labs’s /usr/web/sources/plan9/sys/src/libventi/debug.c
#include <u.h> #include <libc.h> #include <venti.h> void vtdebug(VtConn *z, char *fmt, ...) { va_list arg; if(z->debug == 0) return; va_start(arg, fmt); vfprint(2, fmt, arg); va_end(arg); }