fix doc warning
fix doc warning

cuhkshenzhen/CUHKSZLib,Yexiaoxing/CUHKSZLib,Yexiaoxing/CUHKSZLib,alesiong/CUHKSZLib,Yexiaoxing/CUHKSZLib,cuhkshenzhen/CUHKSZLib,alesiong/CUHKSZLib,cuhkshenzhen/CUHKSZLib,alesiong/CUHKSZLib