/** Time Magazine claimed that "the next full moon on Friday the 13th isn’t expected to happen again for another 30 years—on Aug. 13, 2049" I've found almost every claim of this sort to be wrong, especially when time zones are involved. Let's see if it's right. (Hint: it's right for the continental U.S. but wrong for the "US/Hawaii" timezone.) (Note that this program is quickly hardcoded to an English-speaking locale. If your computer's locale outputs Friday as something other than (Fri) you'll need to change that part of the program.) */ use sun.frink tz = "US/Mountain" d = #2019-09-13# do { f = fullMoon[d] fs = f-> tz if fs =~ %r/\d\d-13 .*(Fri)/ println[fs] d = f + lunarmonth } while d < #2099-09-13#