do_demangle
if (do_demangle(custr_cstr(word), lang, out) < 0)
if (custr_len(word) > 0 && do_demangle(custr_cstr(word), lang, out) < 0)
static int do_demangle(const char *, sysdem_lang_t, FILE *);
if (do_demangle(argv[i], lang, stdout) < 0)