Redis in action, chapter 2

redis-in-action-chap2.py

#!/usr/bin/env python2.6

import time

#
# token cookie
#
def check_token(conn, token):
	return conn.hget('login:', token)

def update_token(conn, token, user, item=None):
	timestamp = time.time()
	conn.hset('login:', token, user)
	conn.zadd('recent:', token, timestamp)
	if item:
		conn.zadd('viewed:' + token, item, timestamp)
		conn.zremrangebyrank('viewed:' + token, 0, -26)
	conn.zincrby('viewed:', item, -1)

LIMIT = 10000000

def clean_sessions(conn):
	#while not QUIT:
	while True:
		size = conn.zcard('recent:')
		if size <= LIMIT:
			time.sleep(1)
			continue

		end_index = min(size - LIMIT, 100)
		sessions = conn.zrange('recent:', 0, end_index - 1)

		vsessions = []
		for sess in sessions:
			vsessions.append('viewed:' + sess)
			vsessions.append('cart:' + sess)

		conn.delete(*vsessions)
		conn.hdel('login:', *sessions)
		conn.zrem('recent:', *sessions)

def add_to_cart(conn, session, item, count):
	if count <= 0:
		conn.hrem('cart:' + session, item)
	else:
		conn.hset('cart:' + session, item, count)

#
# page cache
#
def cache_request(conn, request, callback):
	if not can_cache(conn, request):
		return callback(request)

	page_key = 'cache:' + hash_request(request)
	content = conn.get(page_key)

	if not content:
		content = callback(request)
		conn.setex(page_key, content, 600)

	return content

#
# row cache
#
def schedule_row_cache(conn, rowid, delay):
	conn.zadd('delay:', rowid, delay)
	conn.zadd('schedule:', rowid, time.time())

def cache_rows(conn):
	#while not QUIT:
	while True:
		next = conn.zrange('schedule:', 0, 0, withscores=True)
		if not next or next[0][1] > time.time():
			time.sleep(.05)
			continue

		rowid = next[0][0]
		delay = conn.zscore('delay:', rowid)
		if delay <= 0:
			conn.zrem('delay:', rowid)
			conn.zrem('schedule:', rowid)
			conn.delete('inv:' + rowid)
			continue

		row = Inventory.get(rowid)
		conn.zadd('schedule:', rowid, time.time() + delay)
		conn.set('inv:' + rowid, json.dumps(row.to_dict()))

def rescale_viewed(conn):
	#while not QUIT:
	while True:
		conn.zremrangebyrank('viewed:', 20000, -1)
		conn.zinterstore('viewed:', {'viewed:', .5})
		time.sleep(300)

def can_cache(conn, request):
	itemid = extract_item_id(request)
	if not itemid or is_dynamic(request):
		return False

	rank = conn.zrank('viewed:', itemid)
	return rank is not None and rank < 10000

hey there..i'm newbie to redis as well as into python.
I read first chapter from redis in action abut having trouble to understand the code given in python language.
So, Can you just help me to start over with redis-python?