If the expected operation is to return parking allowed status for a specified date or a weekday, I'd expect the function to return true or false unless the input is malformed (Actually I'd prefer it to return some kind of object that can give more context to the true/false, but I digress).
During normal operation it should never throw an exception. Because if I get an exception, I'll most likely either throw it up the stack or log an error, which will ping someone in PagerDuty if it happens too often.
[0] https://gist.github.com/timvisee/fcda9bbdff88d45cc9061606b4b...
