Open thread, Apr. 17 - Apr. 23, 2017

This is the (late) weekly open thread. See the tag. You’d think we could au­to­mate this. The tra­di­tional boiler­plate fol­lows.

If it’s worth say­ing, but not worth its own post, then it goes here.

Notes for fu­ture OT posters:

1. Please add the ‘open_thread’ tag.

2. Check if there is an ac­tive Open Thread be­fore post­ing a new one. (Im­me­di­ately be­fore; re­fresh the list-of-threads page be­fore post­ing.)

3. Open Threads should start on Mon­day, and end on Sun­day.

4. Un­flag the two op­tions “No­tify me of new top level com­ments on this ar­ti­cle” and “