Most well-known date library systems have failed in places. Quite a few, still do. So whilst you might get some known regression to test against, nothing can gi

Most well-known date library systems have failed in places. Quite a few, still do. So whilst you might get some known regression to test against, nothing can give you a foolproof guide. You can have reasonable confidence that here there be dragons, but not so much that your assumptions about something will hold.