# Reads a byte. Returns a negative value on error
	fun read_byte: Int do
		var llen = lookahead_length
		if llen == 0 then return raw_read_byte
		var lk = lookahead
		var b = lk[0].to_i
		if llen == 1 then
			lookahead_length = 0
		else
			lk.lshift(1, llen - 1, 1)
			lookahead_length -= 1
		end
		return b
	end