size_t *save_idx, struct substring *token);
void ss_advance (struct substring *, size_t);
bool ss_match_char (struct substring *, char);
+bool ss_match_string (struct substring *, const struct substring);
int ss_get_char (struct substring *);
size_t ss_get_chars (struct substring *, size_t cnt, struct substring *);
bool ss_get_until (struct substring *, char delimiter, struct substring *);