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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _iso8601_to_localized_time(date_string):
 """ Convert iso8601 date string into UTC time. :param date_string: iso8601 formatted date string. :return: :class:`datetime.datetime` """

    parsed_date = datetime.strptime(date_string, '%Y-%m-%dT%H:%M:%S.%fZ')
    localized_time = pytz.utc.localize(parsed_date)
    return localized_time