In what context? Something you can check that actually happened and was not predictable? Edit: for example by using big events such as the method mentioned in

In what context? Something you can check that actually happened and was not predictable? Edit: for example by using big events such as the method mentioned in this comment https://news.ycombinator.com/item?id=37565484 https://news.ycombinator.com/item?id=37565484