#define NOARGC  /* no arg count passing */›#define FIXARGC /* don't expect arg counts passed in */›/*›** return 'true' if c is a hexadecimal digit›** (0-9, A-F, or a-f)›*/›isxdigit(c) ›int c; ›$(›  return ((c<='f' && c>='a') ||›          (c<='F' && c>='A') ||›          (c<='9' && c>='0'));›$)›