text: #include <stdarg.h>
  #include <stdio.h>
  
  #define ABC(xyz) ((xyz)+(xyz))
  #define DEF(xyz) ((xyz) \
          +(xyz))
  
  void printMessage(FILE *f, const char *format, ...) {
     va_list ap;
     va_start(ap, format);
     vfprintf(f, format, ap);
     va_end(ap);
  }
  