Invalid unit (valid units are `days`, `hours`, and `minutes`)

Raise code

""" difference between `:MM` and `:SS` is inferred from the
            selected time-unit (e.g. `every().hour.at(':30')` vs.
            `every().minute.at(':30')`).

        :return: The invoked job instance
        """
        if self.unit not in ("days", "hours", "minutes") and not self.start_day:
            raise ScheduleValueError(
                "Invalid unit (valid units are `days`, `hours`, and `minutes`)"
            )
        if not isinstance(time_str, str):
            raise TypeError("at() should be passed a string")
        if self.unit == "days" or self.start_day:
            if not re.match(r"^([0-2]\d:)?[0-5]\d:[0-5]\d$", time_str):
                raise ScheduleValueError(