This gives me the item directly, which is usually what I want when I
call these functions. Save iterators for iterating.
Signed-off-by: Anna Schumaker <anna@ocarinaproject.net>
I updated the design and rewrote the unit tests. This creates something
more consistent with how I ended up using the index.
Signed-off-by: Anna Schumaker <schumaker.anna@gmail.com>