def _parsedate(ymd, hour, year=None):
    # stupidly complicated due to TMY3's usage of hour 24
    # and dateutil's inability to handle that. 
    offset_hour = 1 - int(hour[:2])
    offset_datetime = '{} {}:00'.format(ymd, offset_hour)
    offset_date = dateutil.parser.parse(offset_datetime)
    true_date = offset_date + dateutil.relativedelta.relativedelta(hours=1)
    if year is not None:
        true_date = true_date.replace(year=year)
    return true_date
dataset/ETHPy150Open pvlib/pvlib-python/pvlib/tmy.py/_parsedate/swapped operands of `-`