bool ss_ends_with (struct substring, struct substring suffix);
size_t ss_span (struct substring, struct substring skip_set);
size_t ss_cspan (struct substring, struct substring stop_set);
size_t ss_find_byte (struct substring, char);
bool ss_ends_with (struct substring, struct substring suffix);
size_t ss_span (struct substring, struct substring skip_set);
size_t ss_cspan (struct substring, struct substring stop_set);
size_t ss_find_byte (struct substring, char);