code: func (f PackedFormat) ByteCount(packedIntsVersion, valueCount int32, bitsPerValue uint32) int64 {
  	switch int(f) {
  	case PACKED:
  		if packedIntsVersion < PACKED_VERSION_BYTE_ALIGNED {
  			return 8 * int64(math.Ceil(float64(valueCount)*float64(bitsPerValue)/64))
  		}
  		return int64(math.Ceil(float64(valueCount) * float64(bitsPerValue) / 8))
  	}
  	// assert bitsPerValue >= 0 && bitsPerValue <= 64
  	// assume long-aligned
  	return 8 * int64(f.longCount(packedIntsVersion, valueCount, bitsPerValue))
  }
docs: /**
   * Computes how many byte blocks are needed to store <code>values</code>
   * values of size <code>bitsPerValue</code>.
   */