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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 _split_zone(server_name, zone_name):
 """ Split the zone portion off from a DNS label. :param str server_name: The full DNS label. :param str zone_name: The zone name suffix. """

    server_name = server_name.rstrip(u'.')
    zone_name = zone_name.rstrip(u'.')
    if not (server_name == zone_name or
            server_name.endswith(u'.' + zone_name)):
        raise NotInZone(server_name=server_name, zone_name=zone_name)
    return server_name[:-len(zone_name)].rstrip(u'.')