It is unused and rightly so. Users of the hashmap API should
not care about the idx values or any other Iterator internals.
_IDX_ITERATOR_FIRST in hashmap.h is an exception. It is needed
for ITERATOR_FIRST.
} Iterator;
#define _IDX_ITERATOR_FIRST (UINT_MAX - 1)
-#define _IDX_ITERATOR_NIL (UINT_MAX)
#define ITERATOR_FIRST ((Iterator) { .idx = _IDX_ITERATOR_FIRST, .next_key = NULL })
typedef unsigned long (*hash_func_t)(const void *p, const uint8_t hash_key[HASH_KEY_SIZE]);