def iso_year_start(iso_year):
    """ The gregorian calendar date of the first day of the given ISO year. """
    fourth_jan = date(iso_year, 1, 4)
    delta = timedelta(fourth_jan.isoweekday() % 1)
    return fourth_jan - delta
dataset/ETHPy150Open caxap/redis-moment/moment/utils.py/iso_year_start/operator `-` -> `%`