code: func GetLackHandles(expectedHandles []int64, obtainedHandlesMap map[int64]struct{}) []int64 {
  	diffCnt := len(expectedHandles) - len(obtainedHandlesMap)
  	diffHandles := make([]int64, 0, diffCnt)
  	var cnt int
  	for _, handle := range expectedHandles {
  		isExist := false
  		if _, ok := obtainedHandlesMap[handle]; ok {
  			delete(obtainedHandlesMap, handle)
  			isExist = true
  		}
  		if !isExist {
  			diffHandles = append(diffHandles, handle)
  			cnt++
  			if cnt == diffCnt {
  				break
  			}
  		}
  	}
  
  	return diffHandles
  }
docs: // GetLackHandles gets the handles in expectedHandles but not in obtainedHandlesMap.