int insert_leaf (ISAMB b, struct ISAMB_block **sp1, void *lookahead_item,
int *lookahead_mode, ISAMC_I *stream,
struct ISAMB_block **sp2,
void *sub_item, int *sub_size,
int insert_leaf (ISAMB b, struct ISAMB_block **sp1, void *lookahead_item,
int *lookahead_mode, ISAMC_I *stream,
struct ISAMB_block **sp2,
void *sub_item, int *sub_size,