# Return a `Bytes` by reading 0 and 1.
	#
	#     assert "1010101100001101".binarydigest_to_bytes.hexdigest == "AB0D"
	#
	# Note that characters that are neither 0 or 1 are just ignored.
	#
	#     assert "a1B01 010\n1100あ001101".binarydigest_to_bytes.hexdigest == "AB0D"
	#     assert "hello".binarydigest_to_bytes.is_empty
	#
	# When the number of bits is not divisible by 8, then leading 0 are
	# implicitly considered to fill the left byte (the most significant one).
	#
	#     assert "1".binarydigest_to_bytes.hexdigest == "01"
	#     assert "1111111".binarydigest_to_bytes.hexdigest == "7F"
	#     assert "1000110100".binarydigest_to_bytes.hexdigest == "0234"
	#
	# `Bytes::binarydigest` is a loosely reverse method since its
	# results contain only 1 and 0 by blocks of 8.
	#
	#     assert "1010101100001101".binarydigest_to_bytes.binarydigest == "1010101100001101"
	#     assert "1".binarydigest_to_bytes.binarydigest == "00000001"
	fun binarydigest_to_bytes: Bytes
	do
		var b = bytes
		var max = byte_length

		# Count bits
		var bitlen = 0
		var pos = 0
		while pos < max do
			var c = b[pos]
			pos += 1
			if c == u'0' or c == u'1' then bitlen += 1
		end

		# Allocate (and take care of the padding)
		var ret = new Bytes.with_capacity((bitlen+7) / 8)

		var i = (bitlen+7) % 8 # current bit (7th=128, 0th=1)
		var byte = 0 # current accumulated byte value

		pos = 0
		while pos < max do
			var c = b[pos]
			pos += 1
			if c == u'0' then
				byte = byte << 1
			else if c == u'1' then
				byte = byte << 1 | 1
			else
				continue
			end

			i -= 1
			if i < 0 then
				# Last bit known: store and restart
				ret.add byte
				i = 7
				byte = 0
			end
		end
		return ret
	end