code: func decimalBinSize(precision, frac int) int {
  	digitsInt := precision - frac
  	wordsInt := digitsInt / digitsPerWord
  	wordsFrac := frac / digitsPerWord
  	xInt := digitsInt - wordsInt*digitsPerWord
  	xFrac := frac - wordsFrac*digitsPerWord
  	return wordsInt*wordSize + dig2bytes[xInt] + wordsFrac*wordSize + dig2bytes[xFrac]
  }
docs: // decimalBinSize returns the size of array to hold a binary representation of a decimal.