code: func (ung UniformGenerator) ShuffleRange(arr []interface{}, low, high int) {
  	if low < 0 || low > high || high >= len(arr) {
  		panic(fmt.Sprintf("Illegal subarray range %d ~ %d", low, high))
  	}
  	for i := low; i <= high; i++ {
  		r := int32(i) + ung.Int32n(int32(high-i+1))
  		arr[i], arr[r] = arr[r], arr[i]
  	}
  }
docs: // Shuffle rearrange the elements of the subarray[low..high] in random order