* int PREFIX_compare(SORT_KEY *a, *b)
* compare two keys, result like strcmp
* int PREFIX_fetch_key(struct fastbuf *f, SORT_KEY *k)
- * fetch next key, returns 1=ok, 0=eof
+ * fetch next key, returns nonzero=ok, 0=eof
* void PREFIX_copy_data(struct fastbuf *src, *dest, SORT_KEY *k)
* write just fetched key k to dest and copy all data
* belonging to this key from src to dest.