hfind
e = hfind(hfs, &key, &key);
e = hfind(hfs, &key, &end);
while ((e = hfind(hfs, &key, &end)) != NULL) {
hammer_btree_leaf_elm_t e = hfind(hfs, &key, &key);
hammer_btree_leaf_elm_t e = hfind(hfs, &key, &end);