# Tweet by [@keefmoon](http://twitter.com/keefmoon) on 2013-01-21 18:49:35 > [!INFO] Archived from [original tweet](http://twitter.com/keefmoon/status/293430157740486658) RT @therealkerni: Great post about Blocks, Operations and Retain Cycles: http://t.co/wbn4H3K3