static SkipListNode* create(
NodeAlloc& alloc, int height, U&& data, bool isHead = false) {
DCHECK(height >= 1 && height < 64) << height;
static SkipListNode* create(
NodeAlloc& alloc, int height, U&& data, bool isHead = false) {
DCHECK(height >= 1 && height < 64) << height;