slast
collect_a_seq(size_t uv, uchar_t *u8s, uchar_t **source, uchar_t *slast,
if (s >= slast) {
} else if ((s + sz) > slast) {
for (i = 0; s < slast; )
while (s < slast) {
} else if ((s + sz) > slast) {
&s, slast);
return (_set_current_field(f, snext(slast(f))));