code: func DifferenceUint64Arr(arr [][]uint64) []uint64 {
  	// create a temporary map to hold the contents of the arrays
  	tempMap := make(map[uint64]int)
  	for idx1 := range arr {
  		tempArr := DistinctUint64(arr[idx1])
  		for idx2 := range tempArr {
  			// how many times have we encountered this elem?
  			if _, ok := tempMap[tempArr[idx2]]; ok {
  				tempMap[tempArr[idx2]]++
  			} else {
  				tempMap[tempArr[idx2]] = 1
  			}
  		}
  	}
  
  	// write the final val of the diffMap to an array and return
  	tempArray := make([]uint64, 0)
  	for key, val := range tempMap {
  		if val == 1 {
  			tempArray = append(tempArray, key)
  		}
  	}
  
  	return tempArray
  }
docs: // DifferenceUint64Arr finds the difference of two arrays using a multidimensional array as inputs.
  //
  // Deprecated: use Difference instead.