Thanks (I'm the author). At a high level, the tweak was a big change but I didn't realize it. We used to pre-bill a customer for the next period (e.g., quarter) based upon the previous period's usage. So if you go from 10 users to 20, then in the next period, we'd pre-bill for 20. This obviously is great in that it captures maximize cash flow upfront but it's tricky in that you need to use usage that you're getting right now to calculate future bills. In addition, the variety of our billing plans and legacy customers made this more complicated. Truth be told, I don't think I even fully understood the complexity (my finance and engineering team could give the full story).