有懂Python的朋友没，帮忙解释下下面代码的意思。

#!/usr/bin/env python

#	Aug 19 2011

#	Copyleft@2011 Published Under BSD Lisense

#			Ronald Liu

#	lzsdc01@gmail.com

#	FYI  http://lzsblog.appspot.com/%3Fp%3D291001

#

import sys,DNS,base64



def splitList(txt):

	arr = txt.split("\n")

	

	l = []

	for line in arr:

		if (not len(line)): #empty line

			continue

		if (line[0] == "!"): #Comment line

			continue

		elif(line[0:2] =="@@"):#Forbidding line

			continue

		elif(line.find("/")!=-1 or line.find("*")!=-1): #URL is ignored, only domains left

			continue

		

		#In this case, domain name is irrelevant to protocol(http or https)

		elif(line[0:2] =="||"):

			l.append(line[2:])

		elif(line[0] == "."):

			l.append(line[1:])

		else:

			l.append(line)

	

	return l

	

	



#Decode and decorate the input string

f = open("gfwlist.txt","r")

txt = f.read().replace("\n","")

txt = base64.decodestring(txt)



domains = splitList(txt)



#Set default DNS server

DNSServer=['8.8.8.8']

DNS.defaults['server']=DNSServer



DNS.DiscoverNameServers()



#These two varible are used to track the percentage of parsing process.

l = 0

a = len(domains)



for line in domains:

	request=DNS.Request()

	try:

		result=request.req(name=line,qtype="A")

	except DNS.Base.DNSError:

		msg=line+"\tTime Out\n"

	else:

		if not len(result.answers):

			msg=line+"\tNo record\n"

		else:

			msg=line+ "\tBingo\n"

			for i in result.answers:

				if (i["typename"]=='A'):	#Only A record is useful IP

					print line + " " + i["data"]

	print >> sys.stderr, line + msg, l*1.0/a, "%"