title: How to access all scraped items in Scrapy item pipeline?
body: <p>I have an item that has got a rank field that has to be build from analyzing other item class. I don't want to use database or other backend to store them - I just need to access all currently scraped items and do some itertools magic on them - how can I do this after spider finishes but before we export data (so rank field won't be empty)?</p>