+ if (shgetc(f) != '(') {
+ shunget(f);
+ return NAN;
+ }
+ for (i=1; ; i++) {
+ c = shgetc(f);
+ if (c-'0'<10U || c-'A'<26U || c-'a'<26U || c=='_')
+ continue;
+ if (c==')') return NAN;
+ shunget(f);
+ if (!pok) {
+ errno = EINVAL;
+ shlim(f, 0);
+ return 0;
+ }
+ while (i--) shunget(f);
+ return NAN;
+ }