Method first_of

src/pendulum/datetime.py:966–979

Returns an instance set to the first occurrence of a given day of the week in the current unit. If no day_of_week is provided, modify to the first day of the unit. Use the supplied consts to indicate the desired day_of_week, ex. DateTime.MONDAY. Supp

(self, unit: str, day_of_week: WeekDay | None = None)

        return dt

    def first_of(self, unit: str, day_of_week: WeekDay | None = None) -> Self:
        """
        Returns an instance set to the first occurrence
        of a given day of the week in the current unit.
        If no day_of_week is provided, modify to the first day of the unit.
        Use the supplied consts to indicate the desired day_of_week,
        ex. DateTime.MONDAY.

        Supported units are month, quarter and year.
        """
        if unit not in ["month", "quarter", "year"]:
            raise ValueError(f'Invalid unit "{unit}" for first_of()')

        return cast("Self", getattr(self, f"_first_of_{unit}")(day_of_week))

    def last_of(self, unit: str, day_of_week: WeekDay | None = None) -> Self:
        """