def checksumPid(s)
			tmp = crc32(s)
			crc = tmp ^ (tmp >> 16)
			res = s
			l = LETTERS.length
			for i in 0..1 do
				b = crc & 0xFF
				t = b.divmod(l)[0]
				pos = t ^ (b % l)
				res = "#{res}#{LETTERS[pos % l]}"
				crc >>= 8
			end
			res
		end
def checksumPid(s)
			tmp = crc32(s)
			crc = tmp ^ (tmp >> 16)
			res = s
			l = LETTERS.length
			for i in 0..1 do
				b = crc & 0xFF
				t = b.divmod(l)[0]
				pos = t ^ (b % l)
				res = "#{res}#{LETTERS[pos % l]}"
				crc >>= 8
			end
			res
		end
Generates the actual Personal ID (PID) needed to tie/untie content
 (such as .mobi/.azw files) to a specific device.