RB_ROOT
#define RB_EMPTY(head) (RB_ROOT(head) == NULL)
elm != RB_ROOT(head)) { \
elm = RB_ROOT(head); \
elm = RB_ROOT(head); \
RB_ROOT(head) = child; \
RB_ROOT(head) = elm; \
RB_ROOT(head) = child; \
tmp = RB_ROOT(head); \
RB_ROOT(head) = elm; \
struct type *tmp = RB_ROOT(head); \
struct type *tmp = RB_ROOT(head); \
struct type *tmp = RB_ROOT(head); \