code: func (v qrCodeVersion) numDataBits() int {
  	numDataBits := 0
  	for _, b := range v.block {
  		numDataBits += 8 * b.numBlocks * b.numDataCodewords // 8 bits in a byte
  	}
  
  	return numDataBits
  }
docs: // numDataBits returns the data capacity in bits.