app/Date/AbstractCalendarDate.php
public function inValidRange(): bool
    {
        return $this->minimum_julian_day >= $this->calendar->jdStart() && $this->maximum_julian_day <= $this->calendar->jdEnd();
    }
public function inValidRange(): bool
    {
        return $this->minimum_julian_day >= $this->calendar->jdStart() && $this->maximum_julian_day <= $this->calendar->jdEnd();
    }
public function inValidRange ( ) : bool { return $ this -> minimum_julian_day >= $ this -> calendar -> jdStart ( ) && $ this -> maximum_julian_day <= $ this -> calendar -> jdEnd ( ) ; }
Is this date within the valid range of the calendar

@return bool
Is this date within the valid range of the calendar