keys/words/wordcodec.go
func bytelenFromWords(numWords int) (length int, maybeShorter bool) {
	// calculate the max number of complete bytes we could store in this word
	length = 11 * numWords / 8
	// if one less byte would also generate this length, set maybeShorter
	if wordlenFromBytes(length-1) == numWords {
		maybeShorter = true
	}
	return
}
func bytelenFromWords(numWords int) (length int, maybeShorter bool) {
	// calculate the max number of complete bytes we could store in this word
	length = 11 * numWords / 8
	// if one less byte would also generate this length, set maybeShorter
	if wordlenFromBytes(length-1) == numWords {
		maybeShorter = true
	}
	return
}
// given this many words, we will produce this many bytes.
// sometimes there are two possibilities.
// if maybeShorter is true, then represents len OR len-1 bytes