// 右侧第一个 <= cur 的元素, 所以用大于的就弹出
Whenever the User wishes to obtain a credential, she randomly selects a new serial number SN. This value should be long enough that it’s highly unlikely to repeat (across all other users.)
，这一点在体育直播中也有详细论述
# Type conditional checks are boolean compositions of，更多细节参见safew官方下载
At Meta we also heavily rely on that.，这一点在体育直播中也有详细论述