def is_correct(self):
        """Check if the Daterange is correct : weekdays are valid

        :return: True if weekdays are valid, False otherwise
        :rtype: bool
        """
        valid = True
        valid &= self.swday in range(7)
        if not valid:
            logger.error("Error: %s is not a valid day", self.swday)

        valid &= self.ewday in range(7)
        if not valid:
            logger.error("Error: %s is not a valid day", self.ewday)

        return valid