Having our cake and eating it too: "Using iterators to write highly composeable code"

The first column is a pseudo-anonymous hash identifying a user. The second is a pseudo-anonymous hash representing a location. If we eyeball the first 14 lines, we can see that user 1a2ddc2 visited 5f2b932, bd11537, 5890595, 5f2b932, bd11537, then 5890595. Meanwhile, user f1a543f visited 5890595, 5f2b932, bd11537, 5890595, 5f2b932, bd11537, and then 5890595.