aprl 22, 2017 links

https://news.ycombinator.com/item?id=14170041

https://news.ycombinator.com/item?id=14172044


https://news.ycombinator.com/item?id=14168157

https://news.ycombinator.com/item?id=14171985

https://news.ycombinator.com/item?id=14167453