Return the :class:`.Date` that corresponds to the proleptic
        Gregorian ordinal, where ``0001-01-01`` has ordinal 1 and
        ``9999-12-31`` has ordinal 3,652,059. Values outside of this
        range trigger a :exc:`ValueError`. The corresponding instance
        method for the reverse date-to-ordinal transformation is
        :meth:`.to_ordinal`.

def from_ordinal(cls, ordinal):
        """ Return the :class:`.Date` that corresponds to the proleptic
        Gregorian ordinal, where ``0001-01-01`` has ordinal 1 and
        ``9999-12-31`` has ordinal 3,652,059. Values outside of this
        range trigger a :exc:`ValueError`. The corresponding instance
        method for the reverse date-to-ordinal transformation is
        :meth:`.to_ordinal`.
        """
        if ordinal == 0:
            return ZeroDate
        if ordinal >= 736695:
            year = 2018     # Project release year
            month = 1
            day = int(ordinal - 736694)
        elif ordinal >= 719163:
            year = 1970     # Unix epoch
            month = 1
            day = int(ordinal - 719162)
        else:
            year = 1
            month = 1
            day = int(ordinal)
        if day < 1 or day > 3652059:
            # Note: this requires a maximum of 22 bits for storage
            # Could be transferred in 3 bytes.
            raise ValueError("Ordinal out of range (1..3652059)")
        if year < MIN_YEAR or year > MAX_YEAR:
            raise ValueError("Year out of range (%d..%d)" % (MIN_YEAR, MAX_YEAR))
        days_in_year = DAYS_IN_YEAR[year]
        while day > days_in_year:
            day -= days_in_year
            year += 1
            days_in_year = DAYS_IN_YEAR[year]
        days_in_month = DAYS_IN_MONTH[(year, month)]
        while day > days_in_month:
            day -= days_in_month
            month += 1
            days_in_month = DAYS_IN_MONTH[(year, month)]
        year, month, day = _normalize_day(year, month, day)
        return cls.__new(ordinal, year, month, day)