(4) Diff the index keys of two objects.
- int (*diff_objects)(const void *a, const void *b);
+ int (*diff_objects)(const void *object, const void *index_key);
- Return the bit position at which the index keys of two objects differ or
- -1 if they are the same.
+ Return the bit position at which the index key of the specified object
+ differs from the given index key or -1 if they are the same.
(5) Free an object.