order specified by INSERTIONS, then deletes them in the order specified by
DELETIONS, checking the set's contents for correctness after each
operation. */
static void
test_insert_delete (const int insertions[],
const int deletions[],
order specified by INSERTIONS, then deletes them in the order specified by
DELETIONS, checking the set's contents for correctness after each
operation. */
static void
test_insert_delete (const int insertions[],
const int deletions[],