[dspillett]

Also, in common with other massive online properties for instance Amazon, not consistently: changes sometimes roll out a bit at a time so users in different areas get different versions, either due to global roll-out being a staged process or because a UI experiment is being performed. It usually doesn't matter to a well written scraper as the core data is still accessible in the same way despite the UI sugar coat having changed, but sometimes there are significant enough changes under the hood too that the scraper needs to deal with while still supporting the older format(s).