the notebook appears to be broken with "RuntimeError: Natural join requires shared column names."

Oops, fixed this a few weeks ago but then forgot to republish. Should be working now? Ironically, it broke b/c I convinced Jeff Heer that using an inner join with no matches for a cross join in arquero were too dangerous to be useful, forgetting that I was using them myself! (Although I still think they're bad...)

thanks!